Added support to pass in texture type while creating textures. (flutter#175376)

Resolves part of flutter#145027

Author: AthulJoseph27

engine/src/flutter/lib/gpu/lib/src/context.dart

@@ -117,10 +117,20 @@ base class GpuContext extends NativeFieldWrapperClass1 {
     sampleCount = 1,
     TextureCoordinateSystem coordinateSystem =
         TextureCoordinateSystem.renderToTexture,
+
+    /// The type of texture to create.
+    ///
+    /// If not specified, this will be inferred from the `sampleCount`.
+    TextureType? textureType,
     bool enableRenderTargetUsage = true,
     bool enableShaderReadUsage = true,
     bool enableShaderWriteUsage = false,
   }) {
+    final resolvedTextureType =
+        textureType ??
+        ((sampleCount == 1)
+            ? TextureType.texture2D
+            : TextureType.texture2DMultisample);
     Texture result = Texture._initialize(
       this,
       storageMode,
@@ -129,6 +139,7 @@ base class GpuContext extends NativeFieldWrapperClass1 {
       height,
       sampleCount,
       coordinateSystem,
+      resolvedTextureType,
       enableRenderTargetUsage,
       enableShaderReadUsage,
       enableShaderWriteUsage,

engine/src/flutter/lib/gpu/lib/src/formats.dart

@@ -162,3 +162,17 @@ enum StencilOperation {
   /// Decrement the current stencil value by 1. If at zero, set to maximum.
   decrementWrap,
 }
+
+enum TextureType {
+  /// A 2-dimensional texture.
+  texture2D,
+
+  /// A 2-dimensional texture with multisampling enabled.
+  texture2DMultisample,
+
+  /// A cubemap texture.
+  textureCube,
+
+  /// A texture sourced from an external source.
+  textureExternalOES,
+}

engine/src/flutter/lib/gpu/lib/src/texture.dart

@@ -21,6 +21,7 @@ base class Texture extends NativeFieldWrapperClass1 {
     this.height,
     this.sampleCount,
     TextureCoordinateSystem coordinateSystem,
+    this.textureType,
     this.enableRenderTargetUsage,
     this.enableShaderReadUsage,
     this.enableShaderWriteUsage,
@@ -37,6 +38,7 @@ base class Texture extends NativeFieldWrapperClass1 {
       height,
       sampleCount,
       coordinateSystem.index,
+      textureType.index,
       enableRenderTargetUsage,
       enableShaderReadUsage,
       enableShaderWriteUsage,
@@ -50,6 +52,7 @@ base class Texture extends NativeFieldWrapperClass1 {
   final int width;
   final int height;
   final int sampleCount;
+  final TextureType textureType;
 
   /// Enable using this texture as a render pass attachment.
   final bool enableRenderTargetUsage;
@@ -128,6 +131,7 @@ base class Texture extends NativeFieldWrapperClass1 {
       Int,
       Int,
       Int,
+      Int,
       Bool,
       Bool,
       Bool,
@@ -141,6 +145,7 @@ base class Texture extends NativeFieldWrapperClass1 {
     int height,
     int sampleCount,
     int coordinateSystem,
+    int textureType,
     bool enableRenderTargetUsage,
     bool enableShaderReadUsage,
     bool enableShaderWriteUsage,

engine/src/flutter/lib/gpu/texture.cc

@@ -100,6 +100,7 @@ bool InternalFlutterGpu_Texture_Initialize(Dart_Handle wrapper,
                                            int height,
                                            int sample_count,
                                            int coordinate_system,
+                                           int texture_type,
                                            bool enable_render_target_usage,
                                            bool enable_shader_read_usage,
                                            bool enable_shader_write_usage) {
@@ -119,16 +120,20 @@ bool InternalFlutterGpu_Texture_Initialize(Dart_Handle wrapper,
   }
   switch (sample_count) {
     case 1:
-      desc.type = impeller::TextureType::kTexture2D;
       desc.sample_count = impeller::SampleCount::kCount1;
       break;
     case 4:
-      desc.type = impeller::TextureType::kTexture2DMultisample;
       desc.sample_count = impeller::SampleCount::kCount4;
       break;
     default:
       return false;
   }
+  desc.type = static_cast<impeller::TextureType>(texture_type);
+  if (!impeller::IsMultisampleCapable(desc.type) &&
+      desc.sample_count != impeller::SampleCount::kCount1) {
+    return false;
+  }
+
   auto texture =
       gpu_context->GetContext().GetResourceAllocator()->CreateTexture(desc,
                                                                       true);

engine/src/flutter/lib/gpu/texture.h

@@ -58,6 +58,7 @@ extern bool InternalFlutterGpu_Texture_Initialize(
     int height,
     int sample_count,
     int coordinate_system,
+    int texture_type,
     bool enable_render_target_usage,
     bool enable_shader_read_usage,
     bool enable_shader_write_usage);

engine/src/flutter/testing/dart/gpu_test.dart

@@ -285,6 +285,7 @@ void main() async {
     expect(texture.height, 100);
     expect(texture.storageMode, gpu.StorageMode.hostVisible);
     expect(texture.sampleCount, 1);
+    expect(texture.textureType, gpu.TextureType.texture2D);
     expect(texture.format, gpu.PixelFormat.r8g8b8a8UNormInt);
     expect(texture.enableRenderTargetUsage, true);
     expect(texture.enableShaderReadUsage, true);
@@ -293,6 +294,25 @@ void main() async {
     expect(texture.getBaseMipLevelSizeInBytes(), 40000);
   }, skip: !impellerEnabled);
 
+  test(
+    'GpuContext.createTexture fails if invalid sampleCount and texture type is passed.',
+    () async {
+      try {
+        gpu.gpuContext.createTexture(
+          gpu.StorageMode.hostVisible,
+          100,
+          100,
+          sampleCount: 4,
+          textureType: gpu.TextureType.texture2D,
+        );
+        fail('Exception not thrown when creating an invalid texture.');
+      } catch (e) {
+        expect(e.toString(), contains('Texture creation failed'));
+      }
+    },
+    skip: !impellerEnabled,
+  );
+
   test('Texture.overwrite', () async {
     final gpu.Texture texture = gpu.gpuContext.createTexture(gpu.StorageMode.hostVisible, 2, 2);