[Android FrameWork 6.0源码学习] View的重绘过程之Draw - Android

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[Android FrameWork 6.0源码学习] View的重绘过程之Draw(二)

2017-10-13 10:37:01 【大中小】浏览:8811次

Tags：Android FrameWork 6.0 源码学习 View 过程 Draw

t dirty rect for surface insets. dirty.offset(surfaceInsets.left, surfaceInsets.right); } boolean accessibilityFocusDirty = false; final Drawable drawable = mAttachInfo.mAccessibilityFocusDrawable; if (drawable != null) { final Rect bounds = mAttachInfo.mTmpInvalRect; final boolean hasFocus = getAccessibilityFocusedRect(bounds); if (!hasFocus) { bounds.setEmpty(); } if (!bounds.equals(drawable.getBounds())) { accessibilityFocusDirty = true; } } mAttachInfo.mDrawingTime = mChoreographer.getFrameTimeNanos() / TimeUtils.NANOS_PER_MS; if (!dirty.isEmpty() || mIsAnimating || accessibilityFocusDirty) { if (mAttachInfo.mHardwareRenderer != null && mAttachInfo.mHardwareRenderer.isEnabled()) { // If accessibility focus moved, always invalidate the root. boolean invalidateRoot = accessibilityFocusDirty; // Draw with hardware renderer. mIsAnimating = false; if (mHardwareYOffset != yOffset || mHardwareXOffset != xOffset) { mHardwareYOffset = yOffset; mHardwareXOffset = xOffset; invalidateRoot = true; } mResizeAlpha = resizeAlpha; if (invalidateRoot) { mAttachInfo.mHardwareRenderer.invalidateRoot(); } dirty.setEmpty(); mBlockResizeBuffer = false; mAttachInfo.mHardwareRenderer.draw(mView, mAttachInfo, this); } else { // If we get here with a disabled & requested hardware renderer, something went // wrong (an invalidate posted right before we destroyed the hardware surface // for instance) so we should just bail out. Locking the surface with software // rendering at this point would lock it forever and prevent hardware renderer // from doing its job when it comes back. // Before we request a new frame we must however attempt to reinitiliaze the // hardware renderer if it's in requested state. This would happen after an // eglTerminate() for instance. if (mAttachInfo.mHardwareRenderer != null && !mAttachInfo.mHardwareRenderer.isEnabled() && mAttachInfo.mHardwareRenderer.isRequested()) { try { mAttachInfo.mHardwareRenderer.initializeIfNeeded( mWidth, mHeight, mAttachInfo, mSurface, surfaceInsets); } catch (OutOfResourcesException e) { handleOutOfResourcesException(e); return; } mFullRedrawNeeded = true; scheduleTraversals(); return; } 　　　　　//在这个drawSOftWare方法中会调用view的draw方法，之后整个绘画流程就跑起来了 if (!drawSoftware(surface, mAttachInfo, xOffset, yOffset, scalingRequired, dirty)) { return; } } } if (animating) { mFullRedrawNeeded = true; scheduleTraversals(); } }

这个函数在调用view的draw之前做了很多处理，大概总结一下就是view的滚动设置和硬件加速功能绘画还有一些比较深入的属性比如插图之类，这些我们不怎么关心
我们最关心的是 drawSoftWare 方法

private boolean drawSoftware(Surface surface, AttachInfo attachInfo, int xoff, int yoff,
            boolean scalingRequired, Rect dirty) {

        // Draw with software renderer.
        final Canvas canvas;
        try {
            final int left = dirty.left;
            final int top = dirty.top;
            final int right = dirty.right;
            final int bottom = dirty.bottom;
        　　//获取一块画布，这块画布会传递到各个onDraw方法中
            canvas = mSurface.lockCanvas(dirty);

            // The dirty rectangle can be modified by Surface.lockCanvas()
            //noinspection ConstantConditions
            if (left != dirty.left || top != dirty.top || right != dirty.right
                    || bottom != dirty.bottom) {
                attachInfo.mIgnoreDirtyState = true;
            }

            // TODO: Do this in native
            canvas.setDensity(mDensity);
        } catch (Surface.OutOfResourcesException e) {
            handleOutOfResourcesException(e);
            r

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