BaseCanvas

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 == 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()

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);