commit 16ecda5317c40fc3da284952d9b3add34d6763ae
author Chris Craik <ccraik@google.com> Fri Mar 29 10:59:59 2013 -0700
committer Chris Craik <ccraik@google.com> Mon Apr 01 17:21:35 2013 -0700
tree 1b1a5c9a2bd631a4e0878d7c6de6759e8e8e5909
parent 0102443c4f52f2e15fd731c452f0c4745312d448

Update view's alpha and layer docs

bug:8501661

Makes the performance issues and interaction with layer type/paint
more clear.

Additionally, corrects change from 47ab7d6612e2b5b8b66fb261dafef7c91264e173
to still allow displayList alpha to override layer paint

Change-Id: Ic94d75865700820489370461cd8ac9f9077a8d90

libs/hwui/OpenGLRenderer.cpp

diff --git a/libs/hwui/OpenGLRenderer.cpp b/libs/hwui/OpenGLRenderer.cpp
index 4a5785c..1138998 100644
--- a/libs/hwui/OpenGLRenderer.cpp
+++ b/libs/hwui/OpenGLRenderer.cpp
@@ -114,6 +114,7 @@
         mCaches(Caches::getInstance()), mExtensions(Extensions::getInstance()) {
     mDrawModifiers.mShader = NULL;
     mDrawModifiers.mColorFilter = NULL;
+    mDrawModifiers.mOverrideLayerAlpha = 1.0f;
     mDrawModifiers.mHasShadow = false;
     mDrawModifiers.mHasDrawFilter = false;
 
@@ -1074,7 +1075,7 @@
             layer->setFilter(GL_LINEAR, true);
         }
 
-        float alpha = layer->getAlpha() / 255.0f * mSnapshot->alpha;
+        float alpha = getLayerAlpha(layer);
         bool blend = layer->isBlend() || alpha < 1.0f;
         drawTextureMesh(x, y, x + rect.getWidth(), y + rect.getHeight(),
                 layer->getTexture(), alpha, layer->getMode(), blend,
@@ -1112,7 +1113,7 @@
             rects = safeRegion.getArray(&count);
         }
 
-        const float alpha = layer->getAlpha() / 255.0f * mSnapshot->alpha;
+        const float alpha = getLayerAlpha(layer);
         const float texX = 1.0f / float(layer->getWidth());
         const float texY = 1.0f / float(layer->getHeight());
         const float height = rect.getHeight();
@@ -2237,7 +2238,7 @@
         float left, float top, float right, float bottom, SkPaint* paint) {
     int alpha;
     SkXfermode::Mode mode;
-    getAlphaAndModeDirect(paint, &alpha, &mode);
+    getAlphaAndMode(paint, &alpha, &mode);
 
     return drawPatch(bitmap, xDivs, yDivs, colors, width, height, numColors,
             left, top, right, bottom, alpha, mode);
@@ -2990,7 +2991,7 @@
         if (layer->region.isRect()) {
             composeLayerRect(layer, layer->regionRect);
         } else if (layer->mesh) {
-            const float a = layer->getAlpha() / 255.0f * mSnapshot->alpha;
+            const float a = getLayerAlpha(layer);
             setupDraw();
             setupDrawWithTexture();
             setupDrawColor(a, a, a, a);
@@ -3446,10 +3447,24 @@
     TextureVertex::setUV(v++, u2, v2);
 }
 
-void OpenGLRenderer::getAlphaAndMode(SkPaint* paint, int* alpha, SkXfermode::Mode* mode) {
+void OpenGLRenderer::getAlphaAndMode(SkPaint* paint, int* alpha, SkXfermode::Mode* mode) const {
     getAlphaAndModeDirect(paint, alpha,  mode);
+    if (mDrawModifiers.mOverrideLayerAlpha < 1.0f) {
+        // if drawing a layer, ignore the paint's alpha
+        *alpha = mDrawModifiers.mOverrideLayerAlpha;
+    }
     *alpha *= mSnapshot->alpha;
 }
 
+float OpenGLRenderer::getLayerAlpha(Layer* layer) const {
+    float alpha;
+    if (mDrawModifiers.mOverrideLayerAlpha < 1.0f) {
+        alpha = mDrawModifiers.mOverrideLayerAlpha;
+    } else {
+        alpha = layer->getAlpha() / 255.0f;
+    }
+    return alpha * mSnapshot->alpha;
+}
+
 }; // namespace uirenderer
 }; // namespace android