[Viewer] Preserve gesture transformation matrix on slide/backend change

Change-Id: I417fb9b6d6b7c95884dff6871731883fe3736437
Reviewed-on: https://skia-review.googlesource.com/91460
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>

3 files changed, 8 insertions, 3 deletions

diff --git a/include/views/SkTouchGesture.h b/include/views/SkTouchGesture.h
index faadfc1b3d..82f59f2862 100644
--- a/include/views/SkTouchGesture.h
+++ b/include/views/SkTouchGesture.h
@@ -36,6 +36,7 @@ public:
     void touchMoved(void* owner, float x, float y);
     void touchEnd(void* owner);
     void reset();
+    void resetTouchState();
 
     bool isActive() { return fFlinger.isActive(); }
     void stop() { fFlinger.stop(); }
diff --git a/src/views/SkTouchGesture.cpp b/src/views/SkTouchGesture.cpp
index dbcec511b7..4dce06a6f3 100644
--- a/src/views/SkTouchGesture.cpp
+++ b/src/views/SkTouchGesture.cpp
@@ -108,17 +108,21 @@ SkTouchGesture::SkTouchGesture() {
 SkTouchGesture::~SkTouchGesture() {
 }
 
-void SkTouchGesture::reset() {
+void SkTouchGesture::resetTouchState() {
     fIsTransLimited = false;
     fTouches.reset();
     fState = kEmpty_State;
     fLocalM.reset();
-    fGlobalM.reset();
 
     fLastUpMillis = SkTime::GetMSecs() - 2*MAX_DBL_TAP_INTERVAL;
     fLastUpP.set(0, 0);
 }
 
+void SkTouchGesture::reset() {
+    fGlobalM.reset();
+    this->resetTouchState();
+}
+
 void SkTouchGesture::flushLocalM() {
     fGlobalM.postConcat(fLocalM);
     fLocalM.reset();
diff --git a/tools/viewer/Viewer.cpp b/tools/viewer/Viewer.cpp
index 55a025c1ed..68f8a8d4e5 100644
--- a/tools/viewer/Viewer.cpp
+++ b/tools/viewer/Viewer.cpp
@@ -614,7 +614,7 @@ void Viewer::setupCurrentSlide(int previousSlide) {
     // prepare dimensions for image slides
     fSlides[fCurrentSlide]->load(SkIntToScalar(fWindow->width()), SkIntToScalar(fWindow->height()));
 
-    fGesture.reset();
+    fGesture.resetTouchState();
     fDefaultMatrix.reset();
 
     const SkISize slideSize = fSlides[fCurrentSlide]->getDimensions();