SurfaceTexture: fix a getTransformMatrix crash.

This change moves the computation of the transform matrix out of
getTransformMatrix and instead performs the computation when
updateTexImage gets called.  This is needed in order for
getTransformMatrix to succeed even if the buffers have been freed (e.g.
by changing the buffer count) because the computation depends upon the
properties of the current GraphicBuffer.

Change-Id: Ied541ab8747b7ad604f862717135f9a16a816be9
Bug: 4490420

1 files changed, 8 insertions, 2 deletions

diff --git a/libs/gui/SurfaceTexture.cpp b/libs/gui/SurfaceTexture.cpp
index ee97dcfa9c63..2cda4c82dbcf 100644
--- a/libs/gui/SurfaceTexture.cpp
+++ b/libs/gui/SurfaceTexture.cpp
@@ -96,6 +96,7 @@ SurfaceTexture::SurfaceTexture(GLuint tex) :
     sp<ISurfaceComposer> composer(ComposerService::getComposerService());
     mGraphicBufferAlloc = composer->createGraphicBufferAlloc();
     mNextCrop.makeInvalid();
+    memcpy(mCurrentTransformMatrix, mtxIdentity, sizeof(mCurrentTransformMatrix));
 }
 
 SurfaceTexture::~SurfaceTexture() {
@@ -547,6 +548,7 @@ status_t SurfaceTexture::updateTexImage() {
         mCurrentCrop = mSlots[buf].mCrop;
         mCurrentTransform = mSlots[buf].mTransform;
         mCurrentTimestamp = mSlots[buf].mTimestamp;
+        computeCurrentTransformMatrix();
         mDequeueCondition.signal();
     } else {
         // We always bind the texture even if we don't update its contents.
@@ -596,8 +598,12 @@ GLenum SurfaceTexture::getCurrentTextureTarget() const {
 }
 
 void SurfaceTexture::getTransformMatrix(float mtx[16]) {
-    LOGV("SurfaceTexture::getTransformMatrix");
     Mutex::Autolock lock(mMutex);
+    memcpy(mtx, mCurrentTransformMatrix, sizeof(mCurrentTransformMatrix));
+}
+
+void SurfaceTexture::computeCurrentTransformMatrix() {
+    LOGV("SurfaceTexture::computeCurrentTransformMatrix");
 
     float xform[16];
     for (int i = 0; i < 16; i++) {
@@ -684,7 +690,7 @@ void SurfaceTexture::getTransformMatrix(float mtx[16]) {
     // coordinate of 0, so SurfaceTexture must behave the same way.  We don't
     // want to expose this to applications, however, so we must add an
     // additional vertical flip to the transform after all the other transforms.
-    mtxMul(mtx, mtxFlipV, mtxBeforeFlipV);
+    mtxMul(mCurrentTransformMatrix, mtxFlipV, mtxBeforeFlipV);
 }
 
 nsecs_t SurfaceTexture::getTimestamp() {