Fix startup for SampleSlide

When we start up Viewer with a SampleSlide as the first slide, nothing
gets rendered because SampleSlide depends on the backend being
initialized before setting its dimensions. This pushes the first slide's
initialization after the backend creation.

Change-Id: I8f83fe7b3973c40234104f1a83c0a60750694311
Reviewed-on: https://skia-review.googlesource.com/98161
Reviewed-by: Florin Malita <fmalita@chromium.org>
Commit-Queue: Jim Van Verth <jvanverth@google.com>

1 files changed, 22 insertions, 20 deletions

diff --git a/tools/viewer/Viewer.cpp b/tools/viewer/Viewer.cpp
index 8db541c8fd..198f9baab6 100644
--- a/tools/viewer/Viewer.cpp
+++ b/tools/viewer/Viewer.cpp
@@ -380,7 +380,6 @@ Viewer::Viewer(int argc, char** argv, void* platformData)
 
     // set up slides
     this->initSlides();
-    this->setCurrentSlide(this->startupSlide());
     if (FLAGS_list) {
         this->listNames();
     }
@@ -395,6 +394,7 @@ Viewer::Viewer(int argc, char** argv, void* platformData)
     fImGuiGamutPaint.setFilterQuality(kLow_SkFilterQuality);
 
     fWindow->attach(backend_type_for_window(fBackendType));
+    this->setCurrentSlide(this->startupSlide());
 }
 
 void Viewer::initSlides() {
@@ -616,30 +616,32 @@ void Viewer::setCurrentSlide(int slide) {
 }
 
 void Viewer::setupCurrentSlide() {
-    // prepare dimensions for image slides
-    fGesture.resetTouchState();
-    fDefaultMatrix.reset();
-
-    const SkISize slideSize = fSlides[fCurrentSlide]->getDimensions();
-    const SkRect slideBounds = SkRect::MakeIWH(slideSize.width(), slideSize.height());
-    const SkRect windowRect = SkRect::MakeIWH(fWindow->width(), fWindow->height());
-
-    // Start with a matrix that scales the slide to the available screen space
-    if (fWindow->scaleContentToFit()) {
-        if (windowRect.width() > 0 && windowRect.height() > 0) {
-            fDefaultMatrix.setRectToRect(slideBounds, windowRect, SkMatrix::kStart_ScaleToFit);
+    if (fCurrentSlide >= 0) {
+        // prepare dimensions for image slides
+        fGesture.resetTouchState();
+        fDefaultMatrix.reset();
+
+        const SkISize slideSize = fSlides[fCurrentSlide]->getDimensions();
+        const SkRect slideBounds = SkRect::MakeIWH(slideSize.width(), slideSize.height());
+        const SkRect windowRect = SkRect::MakeIWH(fWindow->width(), fWindow->height());
+
+        // Start with a matrix that scales the slide to the available screen space
+        if (fWindow->scaleContentToFit()) {
+            if (windowRect.width() > 0 && windowRect.height() > 0) {
+                fDefaultMatrix.setRectToRect(slideBounds, windowRect, SkMatrix::kStart_ScaleToFit);
+            }
         }
-    }
 
-    // Prevent the user from dragging content so far outside the window they can't find it again
-    fGesture.setTransLimit(slideBounds, windowRect, fDefaultMatrix);
+        // Prevent the user from dragging content so far outside the window they can't find it again
+        fGesture.setTransLimit(slideBounds, windowRect, fDefaultMatrix);
 
-    this->updateTitle();
-    this->updateUIState();
+        this->updateTitle();
+        this->updateUIState();
 
-    fStatsLayer.resetMeasurements();
+        fStatsLayer.resetMeasurements();
 
-    fWindow->inval();
+        fWindow->inval();
+    }
 }
 
 #define MAX_ZOOM_LEVEL  8