Correctly initialize/refresh layers.

Change-Id: Id8cdcf587b13098460f7d4aa1bd17708784d89bb

3 files changed, 16 insertions, 7 deletions

diff --git a/libs/hwui/Layer.h b/libs/hwui/Layer.h
index c527038..60523db 100644
--- a/libs/hwui/Layer.h
+++ b/libs/hwui/Layer.h
@@ -82,6 +82,10 @@ struct Layer {
      * Indicates whether this layer should be blended.
      */
     bool blend;
+    /**
+     * Indicates that this layer has never been used before.
+     */
+    bool empty;
 }; // struct Layer
 
 }; // namespace uirenderer
diff --git a/libs/hwui/LayerCache.cpp b/libs/hwui/LayerCache.cpp
index 39c3111..2770868 100644
--- a/libs/hwui/LayerCache.cpp
+++ b/libs/hwui/LayerCache.cpp
@@ -109,18 +109,16 @@ Layer* LayerCache::get(LayerSize& size) {
 
         layer = new Layer;
         layer->blend = true;
+        layer->empty = true;
 
         glGenTextures(1, &layer->texture);
         glBindTexture(GL_TEXTURE_2D, layer->texture);
 
-        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
-        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
 
         glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
         glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
-
-        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, size.width, size.height, 0,
-                GL_RGBA, GL_UNSIGNED_BYTE, NULL);
     }
 
     return layer;
diff --git a/libs/hwui/OpenGLRenderer.cpp b/libs/hwui/OpenGLRenderer.cpp
index e62a693..e032085 100644
--- a/libs/hwui/OpenGLRenderer.cpp
+++ b/libs/hwui/OpenGLRenderer.cpp
@@ -381,8 +381,15 @@ bool OpenGLRenderer::createLayer(sp<Snapshot> snapshot, float left, float top,
 
     // Copy the framebuffer into the layer
     glBindTexture(GL_TEXTURE_2D, layer->texture);
-    glCopyTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, bounds.left, mHeight - bounds.bottom,
-            bounds.getWidth(), bounds.getHeight(), 0);
+
+    if (layer->empty) {
+        glCopyTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, bounds.left, mHeight - bounds.bottom,
+                bounds.getWidth(), bounds.getHeight(), 0);
+        layer->empty = false;
+    } else {
+        glCopyTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, bounds.left, mHeight - bounds.bottom,
+                bounds.getWidth(), bounds.getHeight());
+    }
 
     if (flags & SkCanvas::kClipToLayer_SaveFlag) {
         if (mSnapshot->clipTransformed(bounds)) setScissorFromClip();