SurfaceFlinger: add a crop to the layer state

This change adds a crop rectangle specified in window coordinates to the layer
state.  The all window pixels outside this crop rectangle are treated as though
they were fully transparent.  This change also adds the plumbing necessary for
WindowManager to set that crop.

Change-Id: I582bc445dc8c97d4c943d4db8d582a6ef5a66081

1 files changed, 39 insertions, 15 deletions

diff --git a/services/surfaceflinger/LayerBase.cpp b/services/surfaceflinger/LayerBase.cpp
index 694ecdef34..81031b14fb 100644
--- a/services/surfaceflinger/LayerBase.cpp
+++ b/services/surfaceflinger/LayerBase.cpp
@@ -93,6 +93,7 @@ void LayerBase::initStates(uint32_t w, uint32_t h, uint32_t flags)
     mCurrentState.flags         = layerFlags;
     mCurrentState.sequence      = 0;
     mCurrentState.transform.set(0, 0);
+    mCurrentState.crop.makeInvalid();
 
     // drawing state & current state are identical
     mDrawingState = mCurrentState;
@@ -172,6 +173,14 @@ bool LayerBase::setFlags(uint8_t flags, uint8_t mask) {
     requestTransaction();
     return true;
 }
+bool LayerBase::setCrop(const Rect& crop) {
+    if (mCurrentState.crop == crop)
+        return false;
+    mCurrentState.sequence++;
+    mCurrentState.crop = crop;
+    requestTransaction();
+    return true;
+}
 
 Rect LayerBase::visibleBounds() const
 {
@@ -229,15 +238,18 @@ void LayerBase::validateVisibility(const Transform& planeTransform)
     const bool transformed = tr.transformed();
     const DisplayHardware& hw(graphicPlane(0).displayHardware());
     const uint32_t hw_h = hw.getHeight();
+    const Rect& crop(s.crop);
 
-    uint32_t w = s.w;
-    uint32_t h = s.h;
+    Rect win(s.w, s.h);
+    if (!crop.isEmpty()) {
+        win.intersect(crop, &win);
+    }
 
     mNumVertices = 4;
-    tr.transform(mVertices[0], 0, 0);
-    tr.transform(mVertices[1], 0, h);
-    tr.transform(mVertices[2], w, h);
-    tr.transform(mVertices[3], w, 0);
+    tr.transform(mVertices[0], win.left,  win.top);
+    tr.transform(mVertices[1], win.left,  win.bottom);
+    tr.transform(mVertices[2], win.right, win.bottom);
+    tr.transform(mVertices[3], win.right, win.top);
     for (size_t i=0 ; i<4 ; i++)
         mVertices[i][1] = hw_h - mVertices[i][1];
 
@@ -260,7 +272,7 @@ void LayerBase::validateVisibility(const Transform& planeTransform)
     mOrientation = tr.getOrientation();
     mPlaneOrientation = planeTransform.getOrientation();
     mTransform = tr;
-    mTransformedBounds = tr.makeBounds(w, h);
+    mTransformedBounds = tr.transform(win);
 }
 
 void LayerBase::lockPageFlip(bool& recomputeVisibleRegions) {
@@ -391,15 +403,27 @@ void LayerBase::drawWithOpenGL(const Region& clip) const
         GLfloat v;
     };
 
+    Rect crop(s.w, s.h);
+    if (!s.crop.isEmpty()) {
+        crop = s.crop;
+    }
+    GLfloat left = GLfloat(crop.left) / GLfloat(s.w);
+    GLfloat top = GLfloat(crop.top) / GLfloat(s.h);
+    GLfloat right = GLfloat(crop.right) / GLfloat(s.w);
+    GLfloat bottom = GLfloat(crop.bottom) / GLfloat(s.h);
+
     TexCoords texCoords[4];
-    texCoords[0].u = 0;
-    texCoords[0].v = 1;
-    texCoords[1].u = 0;
-    texCoords[1].v = 0;
-    texCoords[2].u = 1;
-    texCoords[2].v = 0;
-    texCoords[3].u = 1;
-    texCoords[3].v = 1;
+    texCoords[0].u = left;
+    texCoords[0].v = top;
+    texCoords[1].u = left;
+    texCoords[1].v = bottom;
+    texCoords[2].u = right;
+    texCoords[2].v = bottom;
+    texCoords[3].u = right;
+    texCoords[3].v = top;
+    for (int i = 0; i < 4; i++) {
+        texCoords[i].v = 1.0f - texCoords[i].v;
+    }
 
     glEnableClientState(GL_TEXTURE_COORD_ARRAY);
     glVertexPointer(2, GL_FLOAT, 0, mVertices);