Add GM to prevent mis-drawing of LCD text in SkPictureImageFilters

gm/pictureimagefilter.cpp

Index: gm/pictureimagefilter.cpp
diff --git a/gm/pictureimagefilter.cpp b/gm/pictureimagefilter.cpp
index 8e5f1ef2a675b4776b6f6211a455ca0647bfd538..30586b3dbe796d51dc3733824d4f91cc26c8c12a 100644
--- a/gm/pictureimagefilter.cpp
+++ b/gm/pictureimagefilter.cpp
@@ -37,6 +37,23 @@ static sk_sp<SkPicture> make_picture() {
     return recorder.finishRecordingAsPicture();
 }
 
+// Create a picture that will draw LCD text
+static sk_sp<SkPicture> make_LCD_picture() {
+    SkPictureRecorder recorder;
+    SkCanvas* canvas = recorder.beginRecording(100, 100, nullptr, 0);
+    canvas->clear(SK_ColorTRANSPARENT);
+    SkPaint paint;
+    paint.setLCDRenderText(true);   // want LCD
+    paint.setAntiAlias(true);       // need AA for LCD
+    sk_tool_utils::set_portable_typeface(&paint);
+    paint.setColor(0xFFFFFFFF);
+    // this has to be small enough that it doesn't become a path
+    paint.setTextSize(SkIntToScalar(36));
+    const char* str = "e";
+    canvas->drawText(str, strlen(str), SkIntToScalar(20), SkIntToScalar(70), paint);
+    return recorder.finishRecordingAsPicture();
+}
+
 class PictureImageFilterGM : public skiagm::GM {
 public:
     PictureImageFilterGM() { }
@@ -50,10 +67,11 @@ protected:
 
     void onOnceBeforeDraw() override {
         fPicture = make_picture();
+        fLCDPicture = make_LCD_picture();
     }
 
     void onDraw(SkCanvas* canvas) override {
-        canvas->clear(SK_ColorBLACK);
+        canvas->clear(SK_ColorGRAY);
         {
             SkRect srcRect = SkRect::MakeXYWH(20, 20, 30, 30);
             SkRect emptyRect = SkRect::MakeXYWH(20, 20, 0, 0);
@@ -85,6 +103,26 @@ protected:
             fill_rect_filtered(canvas, bounds, pictureSourceEmptyRect);
             canvas->translate(SkIntToScalar(100), 0);
 
+            // Draw the LCD picture to a layer
+            {
+                SkPaint stroke;
+                stroke.setStyle(SkPaint::kStroke_Style);
+
+                canvas->drawRect(bounds, stroke);
+
+                SkPaint paint;
+                paint.setImageFilter(SkPictureImageFilter::MakeForLocalSpace(
+                                                                        fLCDPicture,
+                                                                        fPicture->cullRect(),
+                                                                        kNone_SkFilterQuality));
+
+                canvas->scale(4, 4);
+                canvas->translate(-0.9f*srcRect.fLeft, -2.45f*srcRect.fTop);
+
+                canvas->saveLayerPreserveLCDTextRequests(&bounds, &paint);
+                canvas->restore();
+            }
+
             canvas->restore();
 
             // Draw the picture scaled
@@ -105,6 +143,7 @@ protected:
 
 private:
     sk_sp<SkPicture> fPicture;
+    sk_sp<SkPicture> fLCDPicture;
 
     typedef GM INHERITED;
 };