BaseCanvas 源码： 这个类是Canvas绘图操作的基类。这里的任何修改都应该伴随着类似于RecordingCanvas的修改。
这个类的目的是在常规JNI和@FastNative JNI之间降低选择的成本，使之仅限于Canvas已经拥有的虚拟调用。
/** @hide */
public abstract class BaseCanvas {
/** 只应在构造函数（或如果是软件Canvas.setBitmap）中分配，由NativeAllocation释放。 @hide */
protected long mNativeCanvasWrapper;
/** 用于确定兼容性缩放何时生效。 @hide */
protected int mScreenDensity = Bitmap.DENSITY_NONE;
/** @hide */
protected int mDensity = Bitmap.DENSITY_NONE;
private boolean mAllowHwBitmapsInSwMode = false;
protected void throwIfCannotDraw(Bitmap bitmap) {
if (bitmap.isRecycled()) {
throw new RuntimeException("Canvas: trying to use a recycled bitmap " + bitmap);
}
if (!bitmap.isPremultiplied() && bitmap.getConfig() == Bitmap.Config.ARGB_8888 &&
bitmap.hasAlpha()) {
throw new RuntimeException("Canvas: trying to use a non-premultiplied bitmap "
+ bitmap);
}
throwIfHwBitmapInSwMode(bitmap);
}protected final static void checkRange(int length, int offset, int count) {
if ((offset | count) < 0 || offset + count > length) {
throw new ArrayIndexOutOfBoundsException();
}
}public boolean isHardwareAccelerated() {
return false;
} /** ***************** drawXXX方法见文章下方代码段 ******************************/
/** @hide */
public void setHwBitmapsInSwModeEnabled(boolean enabled) {
mAllowHwBitmapsInSwMode = enabled;
}/** @hide */
public boolean isHwBitmapsInSwModeEnabled() {
return mAllowHwBitmapsInSwMode;
}/** @hide */
protected void onHwBitmapInSwMode() {
if (!mAllowHwBitmapsInSwMode) {
throw new IllegalArgumentException(
"Software rendering doesn't support hardware bitmaps");
}
}private void throwIfHwBitmapInSwMode(Bitmap bitmap) {
if (!isHardwareAccelerated() && bitmap.getConfig() == Bitmap.Config.HARDWARE) {
onHwBitmapInSwMode();
}
}private void throwIfHasHwBitmapInSwMode(Paint p) {
if (isHardwareAccelerated() || p == null) {
return;
}
throwIfHasHwBitmapInSwMode(p.getShader());
}private void throwIfHasHwBitmapInSwMode(Shader shader) {
if (shader == null) {
return;
}
if (shader instanceof BitmapShader) {
throwIfHwBitmapInSwMode(((BitmapShader) shader).mBitmap);
}
if (shader instanceof ComposeShader) {
throwIfHasHwBitmapInSwMode(((ComposeShader) shader).mShaderA);
throwIfHasHwBitmapInSwMode(((ComposeShader) shader).mShaderB);
}
} /** *****************native drawXXX()方法 见文章下方代码段*************** */
}
drawXXX() 方法，这些方法也在DisplayListCanvas中实现，以便我们可以有选择地应用于它们
draw几何图形
public void drawArc(float left, float top, float right, float bottom, float startAngle,
float sweepAngle, boolean useCenter, @NonNull Paint paint) {
throwIfHasHwBitmapInSwMode(paint);
nDrawArc(mNativeCanvasWrapper, left, top, right, bottom, startAngle, sweepAngle,
useCenter, paint.getNativeInstance());
}public void drawArc(@NonNull RectF oval, float startAngle, float sweepAngle, boolean useCenter,
@NonNull Paint paint) {
throwIfHasHwBitmapInSwMode(paint);
drawArc(oval.left, oval.top, oval.right, oval.bottom, startAngle, sweepAngle, useCenter,
paint);
}public void drawCircle(float cx, float cy, float radius, @NonNull Paint paint) {
throwIfHasHwBitmapInSwMode(paint);
nDrawCircle(mNativeCanvasWrapper, cx, cy, radius, paint.getNativeInstance());
}public void drawLine(float startX, float startY, float stopX, float stopY,
@NonNull Paint paint) {
throwIfHasHwBitmapInSwMode(paint);
nDrawLine(mNativeCanvasWrapper, startX, startY, stopX, stopY, paint.getNativeInstance());
}public void drawLines(@Size(multiple = 4) @NonNull float[] pts, int offset, int count,
@NonNull Paint paint) {
throwIfHasHwBitmapInSwMode(paint);
nDrawLines(mNativeCanvasWrapper, pts, offset, count, paint.getNativeInstance());
}public void drawLines(@Size(multiple = 4) @NonNull float[] pts, @NonNull Paint paint) {
throwIfHasHwBitmapInSwMode(paint);
drawLines(pts, 0, pts.length, paint);
}public void drawOval(float left, float top, float right, float bottom, @NonNull Paint paint) {
throwIfHasHwBitmapInSwMode(paint);
nDrawOval(mNativeCanvasWrapper, left, top, right, bottom, paint.getNativeInstance());
}public void drawOval(@NonNull RectF oval, @NonNull Paint paint) {
if (oval == null) {
throw new NullPointerException();
}
throwIfHasHwBitmapInSwMode(paint);
drawOval(oval.left, oval.top, oval.right, oval.bottom, paint);
}public void drawPoint(float x, float y, @NonNull Paint paint) {
throwIfHasHwBitmapInSwMode(paint);
nDrawPoint(mNativeCanvasWrapper, x, y, paint.getNativeInstance());
}public void drawPoints(@Size(multiple = 2) float[] pts, int offset, int count,
@NonNull Paint paint) {
throwIfHasHwBitmapInSwMode(paint);
nDrawPoints(mNativeCanvasWrapper, pts, offset, count, paint.getNativeInstance());
}public void drawPoints(@Size(multiple = 2) @NonNull float[] pts, @NonNull Paint paint) {
throwIfHasHwBitmapInSwMode(paint);
drawPoints(pts, 0, pts.length, paint);
}public void drawRect(float left, float top, float right, float bottom, @NonNull Paint paint) {
throwIfHasHwBitmapInSwMode(paint);
nDrawRect(mNativeCanvasWrapper, left, top, right, bottom, paint.getNativeInstance());
}public void drawRect(@NonNull Rect r, @NonNull Paint paint) {
throwIfHasHwBitmapInSwMode(paint);
drawRect(r.left, r.top, r.right, r.bottom, paint);
}public void drawRect(@NonNull RectF rect, @NonNull Paint paint) {
throwIfHasHwBitmapInSwMode(paint);
nDrawRect(mNativeCanvasWrapper,
rect.left, rect.top, rect.right, rect.bottom, paint.getNativeInstance());
}public void drawRoundRect(float left, float top, float right, float bottom, float rx, float ry,
@NonNull Paint paint) {
throwIfHasHwBitmapInSwMode(paint);
nDrawRoundRect(mNativeCanvasWrapper, left, top, right, bottom, rx, ry,
paint.getNativeInstance());
}public void drawRoundRect(@NonNull RectF rect, float rx, float ry, @NonNull Paint paint) {
throwIfHasHwBitmapInSwMode(paint);
drawRoundRect(rect.left, rect.top, rect.right, rect.bottom, rx, ry, paint);
}
drawPath
public void drawPath(@NonNull Path path, @NonNull Paint paint) {
throwIfHasHwBitmapInSwMode(paint);
if (path.isSimplePath && path.rects != null) {
nDrawRegion(mNativeCanvasWrapper, path.rects.mNativeRegion, paint.getNativeInstance());
} else {
nDrawPath(mNativeCanvasWrapper, path.readOnlyNI(), paint.getNativeInstance());
}
}
drawText
@Deprecated
public void drawPosText(@NonNull char[] text, int index, int count,
@NonNull @Size(multiple = 2) float[] pos,
@NonNull Paint paint) {
if (index < 0 || index + count > text.length || count * 2 > pos.length) {
throw new IndexOutOfBoundsException();
}
throwIfHasHwBitmapInSwMode(paint);
for (int i = 0;
i < count;
i++) {
drawText(text, index + i, 1, pos[i * 2], pos[i * 2 + 1], paint);
}
}@Deprecated
public void drawPosText(@NonNull String text, @NonNull @Size(multiple = 2) float[] pos,
@NonNull Paint paint) {
throwIfHasHwBitmapInSwMode(paint);
drawPosText(text.toCharArray(), 0, text.length(), pos, paint);
}public void drawText(@NonNull char[] text, int index, int count, float x, float y,
@NonNull Paint paint) {
if ((index | count | (index + count) |
(text.length - index - count)) < 0) {
throw new IndexOutOfBoundsException();
}
throwIfHasHwBitmapInSwMode(paint);
nDrawText(mNativeCanvasWrapper, text, index, count, x, y, paint.mBidiFlags,
paint.getNativeInstance());
}public void drawText(@NonNull CharSequence text, int start, int end, float x, float y,
@NonNull Paint paint) {
if ((start | end | (end - start) | (text.length() - end)) < 0) {
throw new IndexOutOfBoundsException();
}
throwIfHasHwBitmapInSwMode(paint);
if (text instanceof String || text instanceof SpannedString ||
text instanceof SpannableString) {
nDrawText(mNativeCanvasWrapper, text.toString(), start, end, x, y,
paint.mBidiFlags, paint.getNativeInstance());
} else if (text instanceof GraphicsOperations) {
((GraphicsOperations) text).drawText(this, start, end, x, y,
paint);
} else {
char[] buf = TemporaryBuffer.obtain(end - start);
TextUtils.getChars(text, start, end, buf, 0);
nDrawText(mNativeCanvasWrapper, buf, 0, end - start, x, y,
paint.mBidiFlags, paint.getNativeInstance());
TemporaryBuffer.recycle(buf);
}
}public void drawText(@NonNull String text, float x, float y, @NonNull Paint paint) {
throwIfHasHwBitmapInSwMode(paint);
nDrawText(mNativeCanvasWrapper, text, 0, text.length(), x, y, paint.mBidiFlags,
paint.getNativeInstance());
}public void drawText(@NonNull String text, int start, int end, float x, float y,
@NonNull Paint paint) {
if ((start | end | (end - start) | (text.length() - end)) < 0) {
throw new IndexOutOfBoundsException();
}
throwIfHasHwBitmapInSwMode(paint);
nDrawText(mNativeCanvasWrapper, text, start, end, x, y, paint.mBidiFlags,
paint.getNativeInstance());
}public void drawTextOnPath(@NonNull char[] text, int index, int count, @NonNull Path path,
float hOffset, float vOffset, @NonNull Paint paint) {
if (index < 0 || index + count > text.length) {
throw new ArrayIndexOutOfBoundsException();
}
throwIfHasHwBitmapInSwMode(paint);
nDrawTextOnPath(mNativeCanvasWrapper, text, index, count,
path.readOnlyNI(), hOffset, vOffset,
paint.mBidiFlags, paint.getNativeInstance());
}public void drawTextOnPath(@NonNull String text, @NonNull Path path, float hOffset,
float vOffset, @NonNull Paint paint) {
if (text.length() > 0) {
throwIfHasHwBitmapInSwMode(paint);
nDrawTextOnPath(mNativeCanvasWrapper, text, path.readOnlyNI(), hOffset, vOffset,
paint.mBidiFlags, paint.getNativeInstance());
}
}public void drawTextRun(@NonNull char[] text, int index, int count, int contextIndex,
int contextCount, float x, float y, boolean isRtl, @NonNull Paint paint) {if (text == null) {
throw new NullPointerException("text is null");
}
if (paint == null) {
throw new NullPointerException("paint is null");
}
if ((index | count | contextIndex | contextCount | index - contextIndex
| (contextIndex + contextCount) - (index + count)
| text.length - (contextIndex + contextCount)) < 0) {
throw new IndexOutOfBoundsException();
}throwIfHasHwBitmapInSwMode(paint);
nDrawTextRun(mNativeCanvasWrapper, text, index, count, contextIndex, contextCount,
x, y, isRtl, paint.getNativeInstance(), 0 /* measured text */);
}public void drawTextRun(@NonNull CharSequence text, int start, int end, int contextStart,
int contextEnd, float x, float y, boolean isRtl, @NonNull Paint paint) {if (text == null) {
throw new NullPointerException("text is null");
}
if (paint == null) {
throw new NullPointerException("paint is null");
}
if ((start | end | contextStart | contextEnd | start - contextStart | end - start
| contextEnd - end | text.length() - contextEnd) < 0) {
throw new IndexOutOfBoundsException();
}throwIfHasHwBitmapInSwMode(paint);
if (text instanceof String || text instanceof SpannedString ||
text instanceof SpannableString) {
nDrawTextRun(mNativeCanvasWrapper, text.toString(), start, end, contextStart,
contextEnd, x, y, isRtl, paint.getNativeInstance());
} else if (text instanceof GraphicsOperations) {
((GraphicsOperations) text).drawTextRun(this, start, end,
contextStart, contextEnd, x, y, isRtl, paint);
} else {
int contextLen = contextEnd - contextStart;
int len = end - start;
char[] buf = TemporaryBuffer.obtain(contextLen);
TextUtils.getChars(text, contextStart, contextEnd, buf, 0);
long measuredTextPtr = 0;
if (text instanceof PrecomputedText) {
PrecomputedText mt = (PrecomputedText) text;
int paraIndex = mt.findParaIndex(start);
if (end <= mt.getParagraphEnd(paraIndex)) {
// 仅支持同一段落中的文本。
measuredTextPtr = mt.getMeasuredParagraph(paraIndex).getNativePtr();
}
}
nDrawTextRun(mNativeCanvasWrapper, buf, start - contextStart, len,
0, contextLen, x, y, isRtl, paint.getNativeInstance(), measuredTextPtr);
TemporaryBuffer.recycle(buf);
}
}
drawBitmap
public void drawBitmap(@NonNull Bitmap bitmap, float left, float top, @Nullable Paint paint) {
throwIfCannotDraw(bitmap);
throwIfHasHwBitmapInSwMode(paint);
nDrawBitmap(mNativeCanvasWrapper, bitmap, left, top,
paint != null ? paint.getNativeInstance() : 0, mDensity, mScreenDensity,
bitmap.mDensity);
}public void drawBitmap(@NonNull Bitmap bitmap, @NonNull Matrix matrix, @Nullable Paint paint) {
throwIfHasHwBitmapInSwMode(paint);
nDrawBitmapMatrix(mNativeCanvasWrapper, bitmap, matrix.ni(),
paint != null ? paint.getNativeInstance() : 0);
}public void drawBitmap(@NonNull Bitmap bitmap, @Nullable Rect src, @NonNull Rect dst,
@Nullable Paint paint) {
if (dst == null) {
throw new NullPointerException();
}
throwIfCannotDraw(bitmap);
throwIfHasHwBitmapInSwMode(paint);
final long nativePaint = paint == null ? 0 : paint.getNativeInstance();
int left, top, right, bottom;
if (src =https://www.it610.com/article/= null) {
left = top = 0;
right = bitmap.getWidth();
bottom = bitmap.getHeight();
} else {
left = src.left;
right = src.right;
top = src.top;
bottom = src.bottom;
}nDrawBitmap(mNativeCanvasWrapper, bitmap, left, top, right, bottom,
dst.left, dst.top, dst.right, dst.bottom, nativePaint, mScreenDensity,
bitmap.mDensity);
}public void drawBitmap(@NonNull Bitmap bitmap, @Nullable Rect src, @NonNull RectF dst,
@Nullable Paint paint) {
if (dst == null) {
throw new NullPointerException();
}
throwIfCannotDraw(bitmap);
throwIfHasHwBitmapInSwMode(paint);
final long nativePaint = paint == null ? 0 : paint.getNativeInstance();
float left, top, right, bottom;
if (src == null) {
left = top = 0;
right = bitmap.getWidth();
bottom = bitmap.getHeight();
} else {
left = src.left;
right = src.right;
top = src.top;
bottom = src.bottom;
}nDrawBitmap(mNativeCanvasWrapper, bitmap, left, top, right, bottom,
dst.left, dst.top, dst.right, dst.bottom, nativePaint, mScreenDensity,
bitmap.mDensity);
}@Deprecated
public void drawBitmap(@NonNull int[] colors, int offset, int stride, float x, float y,
int width, int height, boolean hasAlpha, @Nullable Paint paint) {
// check for valid input
if (width < 0) {
throw new IllegalArgumentException("width must be >= 0");
}
if (height < 0) {
throw new IllegalArgumentException("height must be >= 0");
}
if (Math.abs(stride) < width) {
throw new IllegalArgumentException("abs(stride) must be >= width");
}
int lastScanline = offset + (height - 1) * stride;
int length = colors.length;
if (offset < 0 || (offset + width > length) || lastScanline < 0
|| (lastScanline + width > length)) {
throw new ArrayIndexOutOfBoundsException();
}
throwIfHasHwBitmapInSwMode(paint);
// 如果没什么可画的，就赶快避开
if (width == 0 || height == 0) {
return;
}
// 打卡到本地进行实际绘图
nDrawBitmap(mNativeCanvasWrapper, colors, offset, stride, x, y, width, height, hasAlpha,
paint != null ? paint.getNativeInstance() : 0);
}@Deprecated
public void drawBitmap(@NonNull int[] colors, int offset, int stride, int x, int y,
int width, int height, boolean hasAlpha, @Nullable Paint paint) {
// 调用通用float版本
drawBitmap(colors, offset, stride, (float) x, (float) y, width, height,
hasAlpha, paint);
}public void drawBitmapMesh(@NonNull Bitmap bitmap, int meshWidth, int meshHeight,
@NonNull float[] verts, int vertOffset, @Nullable int[] colors, int colorOffset,
@Nullable Paint paint) {
if ((meshWidth | meshHeight | vertOffset | colorOffset) < 0) {
throw new ArrayIndexOutOfBoundsException();
}
throwIfHasHwBitmapInSwMode(paint);
if (meshWidth == 0 || meshHeight == 0) {
return;
}
int count = (meshWidth + 1) * (meshHeight + 1);
// 因为每个顶点需要两个浮点数，所以要乘以2
checkRange(verts.length, vertOffset, count * 2);
if (colors != null) {
// 因为每个顶点只需要一种颜色，没有乘以2
checkRange(colors.length, colorOffset, count);
}
nDrawBitmapMesh(mNativeCanvasWrapper, bitmap, meshWidth, meshHeight,
verts, vertOffset, colors, colorOffset,
paint != null ? paint.getNativeInstance() : 0);
}
draw颜色
public void drawARGB(int a, int r, int g, int b) {
drawColor(Color.argb(a, r, g, b));
}public void drawRGB(int r, int g, int b) {
drawColor(Color.rgb(r, g, b));
}public void drawColor(@ColorInt int color) {
nDrawColor(mNativeCanvasWrapper, color, PorterDuff.Mode.SRC_OVER.nativeInt);
}public void drawColor(@ColorInt int color, @NonNull PorterDuff.Mode mode) {
nDrawColor(mNativeCanvasWrapper, color, mode.nativeInt);
}public void drawPaint(@NonNull Paint paint) {
nDrawPaint(mNativeCanvasWrapper, paint.getNativeInstance());
}public void drawPatch(@NonNull NinePatch patch, @NonNull Rect dst, @Nullable Paint paint) {
Bitmap bitmap = patch.getBitmap();
throwIfCannotDraw(bitmap);
throwIfHasHwBitmapInSwMode(paint);
final long nativePaint = paint == null ? 0 : paint.getNativeInstance();
nDrawNinePatch(mNativeCanvasWrapper, bitmap.getNativeInstance(), patch.mNativeChunk,
dst.left, dst.top, dst.right, dst.bottom, nativePaint,
mDensity, patch.getDensity());
}public void drawPatch(@NonNull NinePatch patch, @NonNull RectF dst, @Nullable Paint paint) {
Bitmap bitmap = patch.getBitmap();
throwIfCannotDraw(bitmap);
throwIfHasHwBitmapInSwMode(paint);
final long nativePaint = paint == null ? 0 : paint.getNativeInstance();
nDrawNinePatch(mNativeCanvasWrapper, bitmap.getNativeInstance(), patch.mNativeChunk,
dst.left, dst.top, dst.right, dst.bottom, nativePaint,
mDensity, patch.getDensity());
}public void drawVertices(@NonNull VertexMode mode, int vertexCount, @NonNull float[] verts,
int vertOffset, @Nullable float[] texs, int texOffset, @Nullable int[] colors,
int colorOffset, @Nullable short[] indices, int indexOffset, int indexCount,
@NonNull Paint paint) {
checkRange(verts.length, vertOffset, vertexCount);
if (isHardwareAccelerated()) {
return;
}
if (texs != null) {
checkRange(texs.length, texOffset, vertexCount);
}
if (colors != null) {
checkRange(colors.length, colorOffset, vertexCount / 2);
}
if (indices != null) {
checkRange(indices.length, indexOffset, indexCount);
}
throwIfHasHwBitmapInSwMode(paint);
nDrawVertices(mNativeCanvasWrapper, mode.nativeInt, vertexCount, verts,
vertOffset, texs, texOffset, colors, colorOffset,
indices, indexOffset, indexCount, paint.getNativeInstance());
}
native drawXXX()
【Android|BaseCanvas】JNI注册由android_view_Canvas.cpp处理
private static native void nDrawBitmap(long nativeCanvas, Bitmap bitmap, float left, float top,
long nativePaintOrZero, int canvasDensity, int screenDensity, int bitmapDensity);
private static native void nDrawBitmap(long nativeCanvas, Bitmap bitmap, float srcLeft,
float srcTop,
float srcRight, float srcBottom, float dstLeft, float dstTop, float dstRight,
float dstBottom, long nativePaintOrZero, int screenDensity, int bitmapDensity);
private static native void nDrawBitmap(long nativeCanvas, int[] colors, int offset, int stride,
float x, float y, int width, int height, boolean hasAlpha, long nativePaintOrZero);
private static native void nDrawColor(long nativeCanvas, int color, int mode);
private static native void nDrawPaint(long nativeCanvas, long nativePaint);
private static native void nDrawPoint(long canvasHandle, float x, float y, long paintHandle);
private static native void nDrawPoints(long canvasHandle, float[] pts, int offset, int count,
long paintHandle);
private static native void nDrawLine(long nativeCanvas, float startX, float startY, float stopX,
float stopY, long nativePaint);
private static native void nDrawLines(long canvasHandle, float[] pts, int offset, int count,
long paintHandle);
private static native void nDrawRect(long nativeCanvas, float left, float top, float right,
float bottom, long nativePaint);
private static native void nDrawOval(long nativeCanvas, float left, float top, float right,
float bottom, long nativePaint);
private static native void nDrawCircle(long nativeCanvas, float cx, float cy, float radius,
long nativePaint);
private static native void nDrawArc(long nativeCanvas, float left, float top, float right,
float bottom, float startAngle, float sweep, boolean useCenter, long nativePaint);
private static native void nDrawRoundRect(long nativeCanvas, float left, float top, float right,
float bottom, float rx, float ry, long nativePaint);
private static native void nDrawPath(long nativeCanvas, long nativePath, long nativePaint);
private static native void nDrawRegion(long nativeCanvas, long nativeRegion, long nativePaint);
private static native void nDrawNinePatch(long nativeCanvas, long nativeBitmap, long ninePatch,
float dstLeft, float dstTop, float dstRight, float dstBottom, long nativePaintOrZero,
int screenDensity, int bitmapDensity);
private static native void nDrawBitmapMatrix(long nativeCanvas, Bitmap bitmap,
long nativeMatrix, long nativePaint);
private static native void nDrawBitmapMesh(long nativeCanvas, Bitmap bitmap, int meshWidth,
int meshHeight, float[] verts, int vertOffset, int[] colors, int colorOffset,
long nativePaint);
private static native void nDrawVertices(long nativeCanvas, int mode, int n, float[] verts,
int vertOffset, float[] texs, int texOffset, int[] colors, int colorOffset,
short[] indices, int indexOffset, int indexCount, long nativePaint);
private static native void nDrawText(long nativeCanvas, char[] text, int index, int count,
float x, float y, int flags, long nativePaint);
private static native void nDrawText(long nativeCanvas, String text, int start, int end,
float x, float y, int flags, long nativePaint);
private static native void nDrawTextRun(long nativeCanvas, String text, int start, int end,
int contextStart, int contextEnd, float x, float y, boolean isRtl, long nativePaint);
private static native void nDrawTextRun(long nativeCanvas, char[] text, int start, int count,
int contextStart, int contextCount, float x, float y, boolean isRtl, long nativePaint,
long nativePrecomputedText);
private static native void nDrawTextOnPath(long nativeCanvas, char[] text, int index, int count,
long nativePath, float hOffset, float vOffset, int bidiFlags, long nativePaint);
private static native void nDrawTextOnPath(long nativeCanvas, String text, long nativePath,
float hOffset, float vOffset, int flags, long nativePaint);
