stanford.androidlib.graphics

Class GCanvas

java.lang.Object

android.view.View

stanford.androidlib.SimpleCanvas

stanford.androidlib.graphics.GCanvas

All Implemented Interfaces:

Drawable.Callback, AccessibilityEventSource, KeyEvent.Callback, View.OnKeyListener, View.OnTouchListener, Iterable<GObject>

public abstract class GCanvas
extends SimpleCanvas
implements Iterable<GObject>

A GCanvas is similar to a GraphicsProgram from the Stanford/ACM Java Task Force library. It allows you to add various GObjects to it and will maintain their state for you. You can update/modify the state of the GObjects, and the changes will appear on screen immediately. A GCanvas can also be easily animated, making it a useful basis for simple graphical animations and 2D games.

 public class MyCanvas extends GCanvas {
     ...
     public void init() {
         ...
     }
 }
 

Nested Class Summary

Nested classes/interfaces inherited from class android.view.View

View.AccessibilityDelegate, View.BaseSavedState, View.DragShadowBuilder, View.MeasureSpec, View.OnApplyWindowInsetsListener, View.OnAttachStateChangeListener, View.OnClickListener, View.OnContextClickListener, View.OnCreateContextMenuListener, View.OnDragListener, View.OnFocusChangeListener, View.OnGenericMotionListener, View.OnHoverListener, View.OnKeyListener, View.OnLayoutChangeListener, View.OnLongClickListener, View.OnScrollChangeListener, View.OnSystemUiVisibilityChangeListener, View.OnTouchListener

Field Summary

Fields inherited from class stanford.androidlib.SimpleCanvas

canvas, paint

Fields inherited from class android.view.View

ACCESSIBILITY_LIVE_REGION_ASSERTIVE, ACCESSIBILITY_LIVE_REGION_NONE, ACCESSIBILITY_LIVE_REGION_POLITE, ALPHA, DRAWING_CACHE_QUALITY_AUTO, DRAWING_CACHE_QUALITY_HIGH, DRAWING_CACHE_QUALITY_LOW, EMPTY_STATE_SET, ENABLED_FOCUSED_SELECTED_STATE_SET, ENABLED_FOCUSED_SELECTED_WINDOW_FOCUSED_STATE_SET, ENABLED_FOCUSED_STATE_SET, ENABLED_FOCUSED_WINDOW_FOCUSED_STATE_SET, ENABLED_SELECTED_STATE_SET, ENABLED_SELECTED_WINDOW_FOCUSED_STATE_SET, ENABLED_STATE_SET, ENABLED_WINDOW_FOCUSED_STATE_SET, FIND_VIEWS_WITH_CONTENT_DESCRIPTION, FIND_VIEWS_WITH_TEXT, FOCUS_BACKWARD, FOCUS_DOWN, FOCUS_FORWARD, FOCUS_LEFT, FOCUS_RIGHT, FOCUS_UP, FOCUSABLES_ALL, FOCUSABLES_TOUCH_MODE, FOCUSED_SELECTED_STATE_SET, FOCUSED_SELECTED_WINDOW_FOCUSED_STATE_SET, FOCUSED_STATE_SET, FOCUSED_WINDOW_FOCUSED_STATE_SET, GONE, HAPTIC_FEEDBACK_ENABLED, IMPORTANT_FOR_ACCESSIBILITY_AUTO, IMPORTANT_FOR_ACCESSIBILITY_NO, IMPORTANT_FOR_ACCESSIBILITY_NO_HIDE_DESCENDANTS, IMPORTANT_FOR_ACCESSIBILITY_YES, INVISIBLE, KEEP_SCREEN_ON, LAYER_TYPE_HARDWARE, LAYER_TYPE_NONE, LAYER_TYPE_SOFTWARE, LAYOUT_DIRECTION_INHERIT, LAYOUT_DIRECTION_LOCALE, LAYOUT_DIRECTION_LTR, LAYOUT_DIRECTION_RTL, MEASURED_HEIGHT_STATE_SHIFT, MEASURED_SIZE_MASK, MEASURED_STATE_MASK, MEASURED_STATE_TOO_SMALL, NO_ID, OVER_SCROLL_ALWAYS, OVER_SCROLL_IF_CONTENT_SCROLLS, OVER_SCROLL_NEVER, PRESSED_ENABLED_FOCUSED_SELECTED_STATE_SET, PRESSED_ENABLED_FOCUSED_SELECTED_WINDOW_FOCUSED_STATE_SET, PRESSED_ENABLED_FOCUSED_STATE_SET, PRESSED_ENABLED_FOCUSED_WINDOW_FOCUSED_STATE_SET, PRESSED_ENABLED_SELECTED_STATE_SET, PRESSED_ENABLED_SELECTED_WINDOW_FOCUSED_STATE_SET, PRESSED_ENABLED_STATE_SET, PRESSED_ENABLED_WINDOW_FOCUSED_STATE_SET, PRESSED_FOCUSED_SELECTED_STATE_SET, PRESSED_FOCUSED_SELECTED_WINDOW_FOCUSED_STATE_SET, PRESSED_FOCUSED_STATE_SET, PRESSED_FOCUSED_WINDOW_FOCUSED_STATE_SET, PRESSED_SELECTED_STATE_SET, PRESSED_SELECTED_WINDOW_FOCUSED_STATE_SET, PRESSED_STATE_SET, PRESSED_WINDOW_FOCUSED_STATE_SET, ROTATION, ROTATION_X, ROTATION_Y, SCALE_X, SCALE_Y, SCREEN_STATE_OFF, SCREEN_STATE_ON, SCROLL_AXIS_HORIZONTAL, SCROLL_AXIS_NONE, SCROLL_AXIS_VERTICAL, SCROLL_INDICATOR_BOTTOM, SCROLL_INDICATOR_END, SCROLL_INDICATOR_LEFT, SCROLL_INDICATOR_RIGHT, SCROLL_INDICATOR_START, SCROLL_INDICATOR_TOP, SCROLLBAR_POSITION_DEFAULT, SCROLLBAR_POSITION_LEFT, SCROLLBAR_POSITION_RIGHT, SCROLLBARS_INSIDE_INSET, SCROLLBARS_INSIDE_OVERLAY, SCROLLBARS_OUTSIDE_INSET, SCROLLBARS_OUTSIDE_OVERLAY, SELECTED_STATE_SET, SELECTED_WINDOW_FOCUSED_STATE_SET, SOUND_EFFECTS_ENABLED, STATUS_BAR_HIDDEN, STATUS_BAR_VISIBLE, SYSTEM_UI_FLAG_FULLSCREEN, SYSTEM_UI_FLAG_HIDE_NAVIGATION, SYSTEM_UI_FLAG_IMMERSIVE, SYSTEM_UI_FLAG_IMMERSIVE_STICKY, SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN, SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION, SYSTEM_UI_FLAG_LAYOUT_STABLE, SYSTEM_UI_FLAG_LIGHT_STATUS_BAR, SYSTEM_UI_FLAG_LOW_PROFILE, SYSTEM_UI_FLAG_VISIBLE, SYSTEM_UI_LAYOUT_FLAGS, TEXT_ALIGNMENT_CENTER, TEXT_ALIGNMENT_GRAVITY, TEXT_ALIGNMENT_INHERIT, TEXT_ALIGNMENT_TEXT_END, TEXT_ALIGNMENT_TEXT_START, TEXT_ALIGNMENT_VIEW_END, TEXT_ALIGNMENT_VIEW_START, TEXT_DIRECTION_ANY_RTL, TEXT_DIRECTION_FIRST_STRONG, TEXT_DIRECTION_FIRST_STRONG_LTR, TEXT_DIRECTION_FIRST_STRONG_RTL, TEXT_DIRECTION_INHERIT, TEXT_DIRECTION_LOCALE, TEXT_DIRECTION_LTR, TEXT_DIRECTION_RTL, TRANSLATION_X, TRANSLATION_Y, TRANSLATION_Z, VIEW_LOG_TAG, VISIBLE, WINDOW_FOCUSED_STATE_SET, X, Y, Z

Constructor Summary

Constructors

Constructor and Description
GCanvas(Context context, AttributeSet attrs) Required constructor; your canvas subclass must implement a constructor with exactly the same parameters.

Method Summary

Modifier and Type	Method and Description
void	add(GObject obj) Adds the given GObject to this canvas.
void	add(GObject obj, float x, float y) Adds the given GObject to this canvas at the given x/y location.
void	add(GObject obj, GPoint point) Adds the given GObject to this canvas at the given x/y location.
boolean	contains(GObject obj) Returns whether this canvas contains the given graphical object.
void	createDisplayBuffer(int width, int height) Sets the display buffer to a new empty bitmap image of the given size.
Paint	getBackgroundColor() Returns the background color that will be drawn on this canvas.
Bitmap	getDisplayBuffer() Returns the display buffer you previously passed to setDisplayBuffer, or null if none has been set.
GObject	getElement(int index) Returns the graphical object at the specified index, numbering from back (0) to front in the the z ordering.
GObject	getElementAt(float... xy) Returns the GObject found at any of the given x/y locations in this canvas.
GObject	getElementAt(float x, float y) Returns the GObject found at the given x/y location in this canvas.
GObject	getElementAt(GPoint... points) Returns the GObject found at any of the given x/y locations in this canvas.
GObject	getElementAt(GPoint point) Returns the GObject found at the given x/y location in this canvas.
int	getElementCount() Returns the number of graphical objects stored in this canvas.
abstract void	init() Called once after the canvas is put onto the screen.
boolean	isInitialized() Returns true if canvas has already been initialized; that is, if init() has been called.
Iterator<GObject>	iterator() Returns an iterator over the GObjects found in this canvas.
Iterator<GObject>	iterator(boolean copy) Returns an iterator over the GObjects found in this canvas.
void	onAnimateTick() This method is automatically called once for each frame of animation by the AnimationLoop.
protected void	onDraw(Canvas canvas) Draws the canvas; you should not override this method.
protected void	onLayout(boolean changed, int left, int top, int right, int bottom) This view lifecycle method is overridden so that we can ensure that init() is called on the canvas before it is shown.
void	remove(GObject obj) Removes the given graphical object, if it was contained in this canvas.
void	removeAll() Removes all graphical objects from this canvas.
void	sendBackward(GObject obj) Moves the given GObject back/down by 1 in the Z-ordering.
void	sendForward(GObject obj) Moves the given GObject forward/up by 1 in the Z-ordering.
void	sendToBack(GObject obj) Moves the given GObject to the back/bottom of the Z-ordering.
void	sendToFront(GObject obj) Moves the given GObject to the front/top of the Z-ordering.
void	setBackgroundColor(Paint color) Sets a background color that will be drawn on this canvas.
void	setDisplayBuffer(Bitmap bitmap) Sets a display buffer on which to draw.
void	setInitialized(boolean initialized) Helper to flag canvas as initialized or not initialized.

Methods inherited from class stanford.androidlib.SimpleCanvas

animate, animationPause, animationResume, animationStop, createFont, createFont, createFont, createFont, createPaint, createPaint, createPaint, drawBitmap, drawImage, drawOval, drawOval, drawRect, drawRect, drawRoundRect, drawRoundRect, drawString, drawText, drawText, enableKeyboardEvents, getActivity, getAnimationTickCount, getBitmap, getCanvas, getScaledBitmap, getScaledBitmap, getScaledBitmapToHeight, getScaledBitmapToWidth, getSimpleActivity, isAnimated, onDetachedFromWindow, onKey, onTouch, preAnimateTick, rotateBitmap, rotateBitmap, scaleBitmap, scaleBitmap, scaleBitmapToHeight, scaleBitmapToWidth, setAlpha, setColor, setColor, setFont, setFont, setFont, setFontFamily, setFontFileName, setFontSize, setPaintStyle

Methods inherited from class android.view.View

addChildrenForAccessibility, addFocusables, addFocusables, addOnAttachStateChangeListener, addOnLayoutChangeListener, addTouchables, animate, announceForAccessibility, awakenScrollBars, awakenScrollBars, awakenScrollBars, bringToFront, buildDrawingCache, buildDrawingCache, buildLayer, callOnClick, cancelLongPress, cancelPendingInputEvents, canResolveLayoutDirection, canResolveTextAlignment, canResolveTextDirection, canScrollHorizontally, canScrollVertically, checkInputConnectionProxy, clearAnimation, clearFocus, combineMeasuredStates, computeHorizontalScrollExtent, computeHorizontalScrollOffset, computeHorizontalScrollRange, computeScroll, computeSystemWindowInsets, computeVerticalScrollExtent, computeVerticalScrollOffset, computeVerticalScrollRange, createAccessibilityNodeInfo, createContextMenu, destroyDrawingCache, dispatchApplyWindowInsets, dispatchConfigurationChanged, dispatchDisplayHint, dispatchDragEvent, dispatchDraw, dispatchDrawableHotspotChanged, dispatchGenericFocusedEvent, dispatchGenericMotionEvent, dispatchGenericPointerEvent, dispatchHoverEvent, dispatchKeyEvent, dispatchKeyEventPreIme, dispatchKeyShortcutEvent, dispatchNestedFling, dispatchNestedPreFling, dispatchNestedPrePerformAccessibilityAction, dispatchNestedPreScroll, dispatchNestedScroll, dispatchPopulateAccessibilityEvent, dispatchProvideStructure, dispatchRestoreInstanceState, dispatchSaveInstanceState, dispatchSetActivated, dispatchSetPressed, dispatchSetSelected, dispatchSystemUiVisibilityChanged, dispatchTouchEvent, dispatchTrackballEvent, dispatchUnhandledMove, dispatchVisibilityChanged, dispatchWindowFocusChanged, dispatchWindowSystemUiVisiblityChanged, dispatchWindowVisibilityChanged, draw, drawableHotspotChanged, drawableStateChanged, findFocus, findViewById, findViewsWithText, findViewWithTag, fitSystemWindows, focusSearch, forceLayout, generateViewId, getAccessibilityClassName, getAccessibilityLiveRegion, getAccessibilityNodeProvider, getAccessibilityTraversalAfter, getAccessibilityTraversalBefore, getAlpha, getAnimation, getApplicationWindowToken, getBackground, getBackgroundTintList, getBackgroundTintMode, getBaseline, getBottom, getBottomFadingEdgeStrength, getBottomPaddingOffset, getCameraDistance, getClipBounds, getClipBounds, getClipToOutline, getContentDescription, getContext, getContextMenuInfo, getDefaultSize, getDisplay, getDrawableState, getDrawingCache, getDrawingCache, getDrawingCacheBackgroundColor, getDrawingCacheQuality, getDrawingRect, getDrawingTime, getElevation, getFilterTouchesWhenObscured, getFitsSystemWindows, getFocusables, getFocusedRect, getForeground, getForegroundGravity, getForegroundTintList, getForegroundTintMode, getGlobalVisibleRect, getGlobalVisibleRect, getHandler, getHeight, getHitRect, getHorizontalFadingEdgeLength, getHorizontalScrollbarHeight, getId, getImportantForAccessibility, getKeepScreenOn, getKeyDispatcherState, getLabelFor, getLayerType, getLayoutDirection, getLayoutParams, getLeft, getLeftFadingEdgeStrength, getLeftPaddingOffset, getLocalVisibleRect, getLocationInWindow, getLocationOnScreen, getMatrix, getMeasuredHeight, getMeasuredHeightAndState, getMeasuredState, getMeasuredWidth, getMeasuredWidthAndState, getMinimumHeight, getMinimumWidth, getNextFocusDownId, getNextFocusForwardId, getNextFocusLeftId, getNextFocusRightId, getNextFocusUpId, getOnFocusChangeListener, getOutlineProvider, getOverlay, getOverScrollMode, getPaddingBottom, getPaddingEnd, getPaddingLeft, getPaddingRight, getPaddingStart, getPaddingTop, getParent, getParentForAccessibility, getPivotX, getPivotY, getResources, getRight, getRightFadingEdgeStrength, getRightPaddingOffset, getRootView, getRootWindowInsets, getRotation, getRotationX, getRotationY, getScaleX, getScaleY, getScrollBarDefaultDelayBeforeFade, getScrollBarFadeDuration, getScrollBarSize, getScrollBarStyle, getScrollIndicators, getScrollX, getScrollY, getSolidColor, getStateListAnimator, getSuggestedMinimumHeight, getSuggestedMinimumWidth, getSystemUiVisibility, getTag, getTag, getTextAlignment, getTextDirection, getTop, getTopFadingEdgeStrength, getTopPaddingOffset, getTouchables, getTouchDelegate, getTransitionName, getTranslationX, getTranslationY, getTranslationZ, getVerticalFadingEdgeLength, getVerticalScrollbarPosition, getVerticalScrollbarWidth, getViewTreeObserver, getVisibility, getWidth, getWindowAttachCount, getWindowId, getWindowSystemUiVisibility, getWindowToken, getWindowVisibility, getWindowVisibleDisplayFrame, getX, getY, getZ, hasFocus, hasFocusable, hasNestedScrollingParent, hasOnClickListeners, hasOverlappingRendering, hasTransientState, hasWindowFocus, inflate, invalidate, invalidate, invalidate, invalidateDrawable, invalidateOutline, isAccessibilityFocused, isActivated, isAttachedToWindow, isClickable, isContextClickable, isDirty, isDrawingCacheEnabled, isDuplicateParentStateEnabled, isEnabled, isFocusable, isFocusableInTouchMode, isFocused, isHapticFeedbackEnabled, isHardwareAccelerated, isHorizontalFadingEdgeEnabled, isHorizontalScrollBarEnabled, isHovered, isImportantForAccessibility, isInEditMode, isInLayout, isInTouchMode, isLaidOut, isLayoutDirectionResolved, isLayoutRequested, isLongClickable, isNestedScrollingEnabled, isOpaque, isPaddingOffsetRequired, isPaddingRelative, isPressed, isSaveEnabled, isSaveFromParentEnabled, isScrollbarFadingEnabled, isScrollContainer, isSelected, isShown, isSoundEffectsEnabled, isTextAlignmentResolved, isTextDirectionResolved, isVerticalFadingEdgeEnabled, isVerticalScrollBarEnabled, jumpDrawablesToCurrentState, layout, measure, mergeDrawableStates, offsetLeftAndRight, offsetTopAndBottom, onAnimationEnd, onAnimationStart, onApplyWindowInsets, onAttachedToWindow, onCancelPendingInputEvents, onCheckIsTextEditor, onConfigurationChanged, onCreateContextMenu, onCreateDrawableState, onCreateInputConnection, onDisplayHint, onDragEvent, onDrawForeground, onDrawScrollBars, onFilterTouchEventForSecurity, onFinishInflate, onFinishTemporaryDetach, onFocusChanged, onGenericMotionEvent, onHoverChanged, onHoverEvent, onInitializeAccessibilityEvent, onInitializeAccessibilityNodeInfo, onKeyDown, onKeyLongPress, onKeyMultiple, onKeyPreIme, onKeyShortcut, onKeyUp, onMeasure, onOverScrolled, onPopulateAccessibilityEvent, onProvideStructure, onProvideVirtualStructure, onRestoreInstanceState, onRtlPropertiesChanged, onSaveInstanceState, onScreenStateChanged, onScrollChanged, onSetAlpha, onSizeChanged, onStartTemporaryDetach, onTouchEvent, onTrackballEvent, onVisibilityChanged, onWindowFocusChanged, onWindowSystemUiVisibilityChanged, onWindowVisibilityChanged, overScrollBy, performAccessibilityAction, performClick, performContextClick, performHapticFeedback, performHapticFeedback, performLongClick, playSoundEffect, post, postDelayed, postInvalidate, postInvalidate, postInvalidateDelayed, postInvalidateDelayed, postInvalidateOnAnimation, postInvalidateOnAnimation, postOnAnimation, postOnAnimationDelayed, refreshDrawableState, removeCallbacks, removeOnAttachStateChangeListener, removeOnLayoutChangeListener, requestApplyInsets, requestFitSystemWindows, requestFocus, requestFocus, requestFocus, requestFocusFromTouch, requestLayout, requestRectangleOnScreen, requestRectangleOnScreen, requestUnbufferedDispatch, resolveSize, resolveSizeAndState, restoreHierarchyState, saveHierarchyState, scheduleDrawable, scrollBy, scrollTo, sendAccessibilityEvent, sendAccessibilityEventUnchecked, setAccessibilityDelegate, setAccessibilityLiveRegion, setAccessibilityTraversalAfter, setAccessibilityTraversalBefore, setActivated, setAlpha, setAnimation, setBackground, setBackgroundColor, setBackgroundDrawable, setBackgroundResource, setBackgroundTintList, setBackgroundTintMode, setBottom, setCameraDistance, setClickable, setClipBounds, setClipToOutline, setContentDescription, setContextClickable, setDrawingCacheBackgroundColor, setDrawingCacheEnabled, setDrawingCacheQuality, setDuplicateParentStateEnabled, setElevation, setEnabled, setFadingEdgeLength, setFilterTouchesWhenObscured, setFitsSystemWindows, setFocusable, setFocusableInTouchMode, setForeground, setForegroundGravity, setForegroundTintList, setForegroundTintMode, setHapticFeedbackEnabled, setHasTransientState, setHorizontalFadingEdgeEnabled, setHorizontalScrollBarEnabled, setHovered, setId, setImportantForAccessibility, setKeepScreenOn, setLabelFor, setLayerPaint, setLayerType, setLayoutDirection, setLayoutParams, setLeft, setLongClickable, setMeasuredDimension, setMinimumHeight, setMinimumWidth, setNestedScrollingEnabled, setNextFocusDownId, setNextFocusForwardId, setNextFocusLeftId, setNextFocusRightId, setNextFocusUpId, setOnApplyWindowInsetsListener, setOnClickListener, setOnContextClickListener, setOnCreateContextMenuListener, setOnDragListener, setOnFocusChangeListener, setOnGenericMotionListener, setOnHoverListener, setOnKeyListener, setOnLongClickListener, setOnScrollChangeListener, setOnSystemUiVisibilityChangeListener, setOnTouchListener, setOutlineProvider, setOverScrollMode, setPadding, setPaddingRelative, setPivotX, setPivotY, setPressed, setRight, setRotation, setRotationX, setRotationY, setSaveEnabled, setSaveFromParentEnabled, setScaleX, setScaleY, setScrollBarDefaultDelayBeforeFade, setScrollBarFadeDuration, setScrollbarFadingEnabled, setScrollBarSize, setScrollBarStyle, setScrollContainer, setScrollIndicators, setScrollIndicators, setScrollX, setScrollY, setSelected, setSoundEffectsEnabled, setStateListAnimator, setSystemUiVisibility, setTag, setTag, setTextAlignment, setTextDirection, setTop, setTouchDelegate, setTransitionName, setTranslationX, setTranslationY, setTranslationZ, setVerticalFadingEdgeEnabled, setVerticalScrollBarEnabled, setVerticalScrollbarPosition, setVisibility, setWillNotCacheDrawing, setWillNotDraw, setX, setY, setZ, showContextMenu, startActionMode, startActionMode, startAnimation, startDrag, startNestedScroll, stopNestedScroll, toString, unscheduleDrawable, unscheduleDrawable, verifyDrawable, willNotCacheDrawing, willNotDraw

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface java.lang.Iterable

forEach, spliterator

Constructor Detail

GCanvas

public GCanvas(Context context,
               AttributeSet attrs)

Required constructor; your canvas subclass must implement a constructor with exactly the same parameters.

Method Detail

add

public void add(GObject obj)

Adds the given GObject to this canvas. On every repaint / onDraw operation, all added GObjects will be drawn.

Throws:

NullPointerException - if obj is null

add

public void add(GObject obj,
                float x,
                float y)

Adds the given GObject to this canvas at the given x/y location. On every repaint / onDraw operation, all added GObjects will be drawn.

Throws:

NullPointerException - if obj is null

add

public void add(GObject obj,
                GPoint point)

Adds the given GObject to this canvas at the given x/y location. On every repaint / onDraw operation, all added GObjects will be drawn.

Throws:

NullPointerException - if obj or point is null

contains

public boolean contains(GObject obj)

Returns whether this canvas contains the given graphical object.

Throws:

NullPointerException - if obj is null

getElementAt

public GObject getElementAt(float x,
                            float y)

Returns the GObject found at the given x/y location in this canvas. If no object touches that location, null is returned. If multiple objects touch that loaction, the highest one in the Z-ordering is returned.

getElementAt

public GObject getElementAt(GPoint point)

Returns the GObject found at the given x/y location in this canvas. If no object touches that location, null is returned. If multiple objects touch that loaction, the highest one in the Z-ordering is returned.

Throws:

NullPointerException - if the point is null

getElementAt

public GObject getElementAt(float... xy)

Returns the GObject found at any of the given x/y locations in this canvas. The locations are treated as {x1, y1, x2, y2, ...} and are tried in order. If no object touches any of these locations, null is returned. If multiple objects touch the first found loaction, the highest one in the Z-ordering is returned.

getElementAt

public GObject getElementAt(GPoint... points)

Returns the GObject found at any of the given x/y locations in this canvas. The locations are tried in order. If no object touches any of these locations, null is returned. If multiple objects touch the first found loaction, the highest one in the Z-ordering is returned.

Throws:

NullPointerException - if any point is null

getElement

public GObject getElement(int index)

Returns the graphical object at the specified index, numbering from back (0) to front in the the z ordering.

Throws:

IndexOutOfBoundsException - if index is negative or exceeds number of objects in canvas

getElementCount

public int getElementCount()

Returns the number of graphical objects stored in this canvas.

onDraw

protected final void onDraw(Canvas canvas)

Draws the canvas; you should not override this method. If you want to draw things onto a GCanvas, you have to do it by adding GObjects to the canvas which are then drawn. If you want to override this method, you should probably be extending SimpleCanvas instead or writing your own custom View subclass.

Overrides:

onDraw in class View

remove

public void remove(GObject obj)

Removes the given graphical object, if it was contained in this canvas.

Throws:

NullPointerException - if obj is null

removeAll

public void removeAll()

Removes all graphical objects from this canvas.

sendBackward

public void sendBackward(GObject obj)

Moves the given GObject back/down by 1 in the Z-ordering. If the given GObject is not added to this canvas, has no effect.

Throws:

NullPointerException - if obj is null

sendForward

public void sendForward(GObject obj)

Moves the given GObject forward/up by 1 in the Z-ordering. If the given GObject is not added to this canvas, has no effect.

Throws:

NullPointerException - if obj is null

sendToBack

public void sendToBack(GObject obj)

Moves the given GObject to the back/bottom of the Z-ordering. If the given GObject is not added to this canvas, has no effect.

Throws:

NullPointerException - if obj is null

sendToFront

public void sendToFront(GObject obj)

Moves the given GObject to the front/top of the Z-ordering. If the given GObject is not added to this canvas, has no effect.

Throws:

NullPointerException - if obj is null

isInitialized

public boolean isInitialized()

Returns true if canvas has already been initialized; that is, if init() has been called.

iterator

public Iterator<GObject> iterator()

Returns an iterator over the GObjects found in this canvas.

Specified by:

iterator in interface Iterable<GObject>

Returns:

an Iterator.

iterator

public Iterator<GObject> iterator(boolean copy)

Returns an iterator over the GObjects found in this canvas. If the copy flag passed is true (default), makes a copy of the internal list of GObjects so that you will not receive a ConcurrentModificationException if you try to add/remove GObjects during a for-each loop over a GCanvas. If the copy flag passed is false, iterates over the actual internal array list of GObjects inside this canvas.

getBackgroundColor

public Paint getBackgroundColor()

Returns the background color that will be drawn on this canvas. If no background has been set, the default background is white.

setBackgroundColor

public void setBackgroundColor(Paint color)

Sets a background color that will be drawn on this canvas. If no background has been set, the default background is white.

Throws:

NullPointerException - if color is null

setInitialized

public void setInitialized(boolean initialized)

Helper to flag canvas as initialized or not initialized. You probably should not call this directly.

init

public abstract void init()

Called once after the canvas is put onto the screen. This method is here for compatibility with the Stanford ACM Java library. You can put code here to initialize your various shapes and drawings.

The main reason you might want to put initialization code here, rather than in the canvas constructor, is because the canvas doesn't yet know its width/height and some other attributes at constructor time, but it does know those things when init() is called.

onAnimateTick

public void onAnimateTick()

This method is automatically called once for each frame of animation by the AnimationLoop. Your canvas class should override this method to contain any code you want to run each frame of animation. The idea is that you should put a SINGLE frame's worth of work inside here, not an entire game loop. The game animation loop is being done for you implicitly by GCanvas and AnimationLoop classes when you call animate().

Overrides:

onAnimateTick in class SimpleCanvas

getDisplayBuffer

public Bitmap getDisplayBuffer()

Returns the display buffer you previously passed to setDisplayBuffer, or null if none has been set.

setDisplayBuffer

public void setDisplayBuffer(Bitmap bitmap)

Sets a display buffer on which to draw. If you set this, all onDraw calls will draw onto the given bitmap image, and then the bitmap will be scaled and drawn onto the canvas. Initially the display buffer is null; call setDisplayBuffer(null); to turn off scaled drawing.

createDisplayBuffer

public void createDisplayBuffer(int width,
                                int height)

Sets the display buffer to a new empty bitmap image of the given size. Equivalent to calling Bitmap.createBitmap and then passing the result to setDisplayBuffer.

onLayout

protected void onLayout(boolean changed,
                        int left,
                        int top,
                        int right,
                        int bottom)

This view lifecycle method is overridden so that we can ensure that init() is called on the canvas before it is shown.

Overrides:

onLayout in class View