Add helper functions make_shader(), make_skimage/skcanvas_for_docimage()

These functions can be used to create a new Skia shader from SkSL
code, and a new SkImage/SkCanvas to modify a doc::Image*

src/app/CMakeLists.txt

@@ -699,6 +699,7 @@ add_library(app-lib
   util/range_utils.cpp
   util/readable_time.cpp
   util/resize_image.cpp
+  util/shader_helpers.cpp
   util/tile_flags_utils.cpp
   util/tileset_utils.cpp
   util/wrap_point.cpp

src/app/render/shader_renderer.cpp

@@ -1,5 +1,5 @@
 // Aseprite
-// Copyright (C) 2022-2023  Igara Studio S.A.
+// Copyright (C) 2022-2024  Igara Studio S.A.
 //
 // This program is distributed under the terms of
 // the End-User License Agreement for Aseprite.
@@ -87,19 +87,9 @@ ShaderRenderer::ShaderRenderer()
   m_properties.renderBgOnScreen = true;
   m_properties.requiresRgbaBackbuffer = true;
 
-  auto makeShader = [](const char* code) {
-    auto result = SkRuntimeEffect::MakeForShader(SkString(code));
-    if (!result.errorText.isEmpty()) {
-      LOG(ERROR, "Shader error: %s\n", result.errorText.c_str());
-      std::printf("Shader error: %s\n", result.errorText.c_str());
-      throw std::runtime_error("Cannot compile shaders for ShaderRenderer");
-    }
-    return result;
-  };
-
-  m_bgEffect = makeShader(kBgShaderCode).effect;
-  m_indexedEffect = makeShader(kIndexedShaderCode).effect;
-  m_grayscaleEffect = makeShader(kGrayscaleShaderCode).effect;
+  m_bgEffect = make_shader(kBgShaderCode);
+  m_indexedEffect = make_shader(kIndexedShaderCode);
+  m_grayscaleEffect = make_shader(kGrayscaleShaderCode);
 }
 
 ShaderRenderer::~ShaderRenderer() = default;
@@ -416,21 +406,11 @@ void ShaderRenderer::drawImage(SkCanvas* canvas,
                                const int opacity,
                                const doc::BlendMode blendMode)
 {
-  auto skData = SkData::MakeWithoutCopy(
-    (const void*)srcImage->getPixelAddress(0, 0),
-    srcImage->rowBytes() * srcImage->height());
+  auto skImg = make_skimage_for_docimage(srcImage);
 
   switch (srcImage->colorMode()) {
 
     case doc::ColorMode::RGB: {
-      auto skImg = SkImage::MakeRasterData(
-        SkImageInfo::Make(srcImage->width(),
-                          srcImage->height(),
-                          kRGBA_8888_SkColorType,
-                          kUnpremul_SkAlphaType),
-        skData,
-        srcImage->rowBytes());
-
       SkPaint p;
       p.setAlpha(opacity);
       p.setBlendMode(to_skia(blendMode));
@@ -443,15 +423,6 @@ void ShaderRenderer::drawImage(SkCanvas* canvas,
     }
 
     case doc::ColorMode::GRAYSCALE: {
-      // We use kR8G8_unorm_SkColorType to access gray and alpha
-      auto skImg = SkImage::MakeRasterData(
-        SkImageInfo::Make(srcImage->width(),
-                          srcImage->height(),
-                          kR8G8_unorm_SkColorType,
-                          kOpaque_SkAlphaType),
-        skData,
-        srcImage->rowBytes());
-
       SkRuntimeShaderBuilder builder(m_grayscaleEffect);
       builder.child("iImg") = skImg->makeRawShader(SkSamplingOptions(SkFilterMode::kNearest));
 
@@ -471,15 +442,6 @@ void ShaderRenderer::drawImage(SkCanvas* canvas,
     }
 
     case doc::ColorMode::INDEXED: {
-      // We use kAlpha_8_SkColorType to access to the index value through the alpha channel
-      auto skImg = SkImage::MakeRasterData(
-        SkImageInfo::Make(srcImage->width(),
-                          srcImage->height(),
-                          kAlpha_8_SkColorType,
-                          kUnpremul_SkAlphaType),
-        skData,
-        srcImage->rowBytes());
-
       // Use the palette data as an "width x height" image where
       // width=number of palette colors, and height=1
       const size_t palSize = sizeof(color_t) * m_palette.size();

src/app/util/shader_helpers.cpp

@@ -0,0 +1,94 @@
+// Aseprite
+// Copyright (C) 2024  Igara Studio S.A.
+//
+// This program is distributed under the terms of
+// the End-User License Agreement for Aseprite.
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#if SK_ENABLE_SKSL
+
+#include "app/util/shader_helpers.h"
+
+#include "base/exception.h"
+#include "doc/image.h"
+#include "fmt/format.h"
+
+#include "include/effects/SkRuntimeEffect.h"
+
+namespace app {
+
+sk_sp<SkRuntimeEffect> make_shader(const char* code)
+{
+  auto result = SkRuntimeEffect::MakeForShader(SkString(code));
+  if (!result.errorText.isEmpty()) {
+    std::string error = fmt::format("Error compiling shader.\nError: {}\n",
+                                    result.errorText.c_str());
+    LOG(ERROR, error.c_str());
+    std::printf("%s", error.c_str());
+    throw base::Exception(error);
+  }
+  return result.effect;
+}
+
+SkImageInfo get_skimageinfo_for_docimage(const doc::Image* img)
+{
+  switch (img->colorMode()) {
+
+    case doc::ColorMode::RGB:
+      return SkImageInfo::Make(img->width(),
+                               img->height(),
+                               kRGBA_8888_SkColorType,
+                               kUnpremul_SkAlphaType);
+
+    case doc::ColorMode::GRAYSCALE:
+      // We use kR8G8_unorm_SkColorType to access gray and alpha
+      return SkImageInfo::Make(img->width(),
+                               img->height(),
+                               kR8G8_unorm_SkColorType,
+                               kOpaque_SkAlphaType);
+
+    case doc::ColorMode::INDEXED: {
+      // We use kAlpha_8_SkColorType to access to the index value through the alpha channel
+      return SkImageInfo::Make(img->width(),
+                               img->height(),
+                               kAlpha_8_SkColorType,
+                               kUnpremul_SkAlphaType);
+
+    }
+  }
+  return SkImageInfo();
+}
+
+sk_sp<SkImage> make_skimage_for_docimage(const doc::Image* img)
+{
+  switch (img->colorMode()) {
+    case doc::ColorMode::RGB:
+    case doc::ColorMode::GRAYSCALE:
+    case doc::ColorMode::INDEXED: {
+      auto skData = SkData::MakeWithoutCopy(
+        (const void*)img->getPixelAddress(0, 0),
+        img->rowBytes() * img->height());
+
+      return SkImage::MakeRasterData(
+        get_skimageinfo_for_docimage(img),
+        skData,
+        img->rowBytes());
+    }
+  }
+  return nullptr;
+}
+
+std::unique_ptr<SkCanvas> make_skcanvas_for_docimage(const doc::Image* img)
+{
+  return SkCanvas::MakeRasterDirect(
+    get_skimageinfo_for_docimage(img),
+    (void*)img->getPixelAddress(0, 0),
+    img->rowBytes());
+}
+
+} // namespace app
+
+#endif // SK_ENABLE_SKSL

src/app/util/shader_helpers.h

@@ -1,5 +1,5 @@
 // Aseprite
-// Copyright (C) 2022  Igara Studio S.A.
+// Copyright (C) 2022-2024  Igara Studio S.A.
 //
 // This program is distributed under the terms of
 // the End-User License Agreement for Aseprite.
@@ -8,18 +8,32 @@
 #define APP_UTIL_SHADER_HELPERS_H_INCLUDED
 #pragma once
 
-#if SK_ENABLE_SKSL
+#if LAF_SKIA
 
 #include "app/color.h"
 #include "gfx/color.h"
 
+#include "include/core/SkCanvas.h"
+#include "include/core/SkImage.h"
 #include "include/core/SkM44.h"
+#include "include/core/SkRefCnt.h"
 
-// To include kRGB_to_HSL_sksl and kHSL_to_RGB_sksl
-#include "src/core/SkRuntimeEffectPriv.h"
+#if SK_ENABLE_SKSL
+  #include "include/effects/SkRuntimeEffect.h"
+  // To include kRGB_to_HSL_sksl and kHSL_to_RGB_sksl
+  #include "src/core/SkRuntimeEffectPriv.h"
+#endif
+
+#include <memory>
+
+namespace doc {
+  class Image;
+}
 
 namespace app {
 
+#if SK_ENABLE_SKSL
+
 // rgb_to_hsl() and hsv_to_hsl() functions by Sam Hocevar licensed
 // under WTFPL (https://en.wikipedia.org/wiki/WTFPL)
 // Source:
@@ -74,8 +88,16 @@ inline SkV4 appColorHsl_to_SkV4(const app::Color& color) {
               float(color.getAlpha() / 255.0)};
 }
 
+sk_sp<SkRuntimeEffect> make_shader(const char* code);
+
+#endif  // SK_ENABLE_SKSL
+
+SkImageInfo get_skimageinfo_for_docimage(const doc::Image* img);
+sk_sp<SkImage> make_skimage_for_docimage(const doc::Image* img);
+std::unique_ptr<SkCanvas> make_skcanvas_for_docimage(const doc::Image* img);
+
 } // namespace app
 
-#endif
+#endif  // LAF_SKIA
 
 #endif