Change how OpenGL textures are flipped in the Android embedder. (#49938)

h/t @bdero for [writing the actual
code](flutter/flutter#141636 (comment))
(I just wrote comments).

Manual test[^1] of `cd
packages/packages/video_player/video_player/example && flutter run`:

## Skia

![Screenshot 2024-01-22 at 3 21
20 PM](https://github.com/flutter/engine/assets/168174/f1023251-4b44-47f3-94f8-1d5dced7bcb3)

## Impeller + OpenGL

![Screenshot 2024-01-22 at 9 41
59 AM](https://github.com/flutter/engine/assets/168174/a2bed578-c929-4222-a1f9-010e2dc95b7e)

```xml
<meta-data
      android:name="io.flutter.embedding.android.EnableImpeller"
      android:value="true" />
<meta-data
      android:name="io.flutter.embedding.android.ImpellerBackend"
      android:value="opengles" />
```

Closes flutter/flutter#141636.

[^1]: I can't write a test worth writing at the same time of this PR, so
I've filed flutter/flutter#141973 to do it
after.

Author: matanlurey

shell/platform/android/surface_texture_external_texture.cc

@@ -58,11 +58,17 @@ void SurfaceTextureExternalTexture::Paint(PaintContext& context,
   if (dl_image_) {
     DlAutoCanvasRestore autoRestore(context.canvas, true);
 
-    // The incoming texture is vertically flipped, so we flip it
-    // back. OpenGL's coordinate system has Positive Y equivalent to up, while
-    // Skia's coordinate system has Negative Y equvalent to up.
-    context.canvas->Translate(bounds.x(), bounds.y() + bounds.height());
-    context.canvas->Scale(bounds.width(), -bounds.height());
+    // The incoming texture is vertically flipped, so we flip it back.
+    //
+    // OpenGL's coordinate system has Positive Y equivalent to up, while Skia's
+    // coordinate system (as well as Impeller's) has Negative Y equvalent to up.
+    {
+      // Move (translate) the origin to the bottom-left corner of the image.
+      context.canvas->Translate(bounds.x(), bounds.y() + bounds.height());
+
+      // No change in the X axis, but we need to flip the Y axis.
+      context.canvas->Scale(1, -1);
+    }
 
     if (!transform_.isIdentity()) {
       DlImageColorSource source(dl_image_, DlTileMode::kRepeat,
@@ -73,7 +79,8 @@ void SurfaceTextureExternalTexture::Paint(PaintContext& context,
         paintWithShader = *context.paint;
       }
       paintWithShader.setColorSource(&source);
-      context.canvas->DrawRect(SkRect::MakeWH(1, 1), paintWithShader);
+      context.canvas->DrawRect(SkRect::MakeWH(bounds.width(), bounds.height()),
+                               paintWithShader);
     } else {
       context.canvas->DrawImage(dl_image_, {0, 0}, sampling, context.paint);
     }

shell/platform/android/surface_texture_external_texture_gl.cc

@@ -48,8 +48,11 @@ void SurfaceTextureExternalTextureGL::ProcessFrame(PaintContext& context,
   // Create a
   GrGLTextureInfo textureInfo = {GL_TEXTURE_EXTERNAL_OES, texture_name_,
                                  GL_RGBA8_OES};
-  auto backendTexture =
-      GrBackendTextures::MakeGL(1, 1, skgpu::Mipmapped::kNo, textureInfo);
+  auto backendTexture = GrBackendTextures::MakeGL(
+      /*width=*/bounds.width(),
+      /*height=*/bounds.height(),
+      /*Mipmapped=*/skgpu::Mipmapped::kNo,
+      /*glInfo=*/textureInfo);
   dl_image_ = DlImage::Make(SkImages::BorrowTextureFrom(
       context.gr_context, backendTexture, kTopLeft_GrSurfaceOrigin,
       kRGBA_8888_SkColorType, kPremul_SkAlphaType, nullptr));