From 782a957f83c0b5f7b6015f5f1b7a2f3553844783 Mon Sep 17 00:00:00 2001
From: Ben Wagner <bungeman@google.com>
Date: Fri, 17 Jan 2020 15:55:14 -0500
Subject: [PATCH] Update fontscalerdistortable to onOnceBeforeDraw.

In viewer fontscalerdistortable spends a large amount of resources
continually recreating typefaces. Instead, just create the needed
typefaces once up front and then use them in onDraw. This also makes it
easier to just check in popular variants for testing how system specific
fonts look.

Change-Id: Ie5f975cd87e87523b6f28ff01ec9ffc726d8b971
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/265148
Commit-Queue: Herb Derby <herb@google.com>
Reviewed-by: Herb Derby <herb@google.com>
---
 gm/fontscalerdistortable.cpp | 77 +++++++++++++++++++++++-------------
 1 file changed, 50 insertions(+), 27 deletions(-)

diff --git a/gm/fontscalerdistortable.cpp b/gm/fontscalerdistortable.cpp
index cfeab90683..6d6c16cf2a 100644
--- a/gm/fontscalerdistortable.cpp
+++ b/gm/fontscalerdistortable.cpp
@@ -44,47 +44,70 @@ private:
         return SkISize::Make(550, 700);
     }
 
+    static constexpr int rows = 2;
+    static constexpr int cols = 5;
+    sk_sp<SkTypeface> typeface[rows][cols];
+    void onOnceBeforeDraw() override {
+        sk_sp<SkFontMgr> fontMgr(SkFontMgr::RefDefault());
+
+        constexpr SkFourByteTag wght = SkSetFourByteTag('w','g','h','t');
+        //constexpr SkFourByteTag wdth = SkSetFourByteTag('w','d','t','h');
+        struct {
+            sk_sp<SkTypeface> distortable;
+            SkFourByteTag axisTag;
+            SkScalar axisMin;
+            SkScalar axisMax;
+        } info = {
+            MakeResourceAsTypeface("fonts/Distortable.ttf"), wght, 0.5f, 2.0f
+            //SkTypeface::MakeFromFile("/Library/Fonts/Skia.ttf"), wght, 0.48f, 3.2f
+            //SkTypeface::MakeFromName("Skia", SkFontStyle()), wdth, 0.62f, 1.3f
+            //SkTypeface::MakeFromFile("/System/Library/Fonts/SFNS.ttf"), wght, 100.0f, 900.0f
+            //SkTypeface::MakeFromName(".SF NS", SkFontStyle()), wght, 100.0f, 900.0f
+        };
+        std::unique_ptr<SkStreamAsset> distortableStream( info.distortable
+                                                        ? info.distortable->openStream(nullptr)
+                                                        : nullptr);
+        for (int row = 0; row < rows; ++row) {
+            for (int col = 0; col < cols; ++col) {
+                SkScalar styleValue = SkScalarInterp(info.axisMin, info.axisMax,
+                                                     SkScalar(row * cols + col) / (rows * cols));
+                SkFontArguments::VariationPosition::Coordinate coordinates[] = {
+                    {info.axisTag, styleValue},
+                    {info.axisTag, styleValue}
+                };
+                SkFontArguments::VariationPosition position = {
+                    coordinates, SK_ARRAY_COUNT(coordinates)
+                };
+                typeface[row][col] = [&]() -> sk_sp<SkTypeface> {
+                    if (row == 0 && info.distortable) {
+                        return info.distortable->makeClone(
+                                SkFontArguments().setVariationDesignPosition(position));
+                    }
+                    if (distortableStream) {
+                        return fontMgr->makeFromStream(distortableStream->duplicate(),
+                                SkFontArguments().setVariationDesignPosition(position));
+                    }
+                    return nullptr;
+                }();
+            }
+        }
+    }
+
     DrawResult onDraw(SkCanvas* canvas, SkString* errorMsg) override {
         SkPaint paint;
         paint.setAntiAlias(true);
         SkFont font;
         font.setEdging(SkFont::Edging::kSubpixelAntiAlias);
-        sk_sp<SkFontMgr> fontMgr(SkFontMgr::RefDefault());
 
-        std::unique_ptr<SkStreamAsset> distortableStream(GetResourceAsStream("fonts/Distortable.ttf"));
-        sk_sp<SkTypeface> distortable(MakeResourceAsTypeface("fonts/Distortable.ttf"));
-
-        if (!distortableStream) {
-            *errorMsg = "No distortableStream";
-            return DrawResult::kFail;
-        }
         const char* text = "abc";
         const size_t textLen = strlen(text);
 
-        SkFourByteTag tag = SkSetFourByteTag('w','g','h','t');
-        constexpr SkScalar tagMin = 0.5f;
-        constexpr SkScalar tagMax = 2.0f;
-        constexpr int rows = 2;
-        constexpr int cols = 5;
         for (int row = 0; row < rows; ++row) {
             for (int col = 0; col < cols; ++col) {
                 SkScalar x = SkIntToScalar(10);
                 SkScalar y = SkIntToScalar(20);
 
-                SkScalar styleValue = SkScalarInterp(tagMin, tagMax,
-                                                     SkScalar(row * cols + col) / (rows * cols));
-                SkFontArguments::VariationPosition::Coordinate coordinates[] = {{tag, styleValue}};
-                SkFontArguments::VariationPosition position =
-                        { coordinates, SK_ARRAY_COUNT(coordinates) };
-                if (row == 0 && distortable) {
-                    sk_sp<SkTypeface> clone = distortable->makeClone(
-                            SkFontArguments().setVariationDesignPosition(position));
-                    font.setTypeface(clone ? std::move(clone) : distortable);
-                } else {
-                    font.setTypeface(fontMgr->makeFromStream(
-                        distortableStream->duplicate(),
-                        SkFontArguments().setVariationDesignPosition(position)));
-                }
+                font.setTypeface(typeface[row][col] ? typeface[row][col] : nullptr);
 
                 SkAutoCanvasRestore acr(canvas, true);
                 canvas->translate(SkIntToScalar(30 + col * 100), SkIntToScalar(20));