LibGL+LibGPU+LibSoftGPU: Implement flexible pixel format conversion

A GPU (driver) is now responsible for reading and writing pixels from
and to user data. The client (LibGL) is responsible for specifying how
the user data must be interpreted or written to.

This allows us to centralize all pixel format conversion in one class,
`LibSoftGPU::PixelConverter`. For both the input and output image, it
takes a specification containing the image dimensions, the pixel type
and the selection (basically a clipping rect), and converts the pixels
from the input image to the output image.

Effectively this means we now support almost all OpenGL 1.5 formats,
and all custom logic has disappeared from:
  - `glDrawPixels`
  - `glReadPixels`
  - `glTexImage2D`
  - `glTexSubImage2D`

The new logic is still unoptimized, but on my machine I experienced no
noticeable slowdown. :^)

Author: gmta

Tests/LibGL/TestRender.cpp

@@ -169,3 +169,33 @@ TEST_CASE(0005_lines_antialiased)
     context->present();
     expect_bitmap_equals_reference(context->frontbuffer(), "0005_lines"sv);
 }
+
+TEST_CASE(0006_test_rgb565_texture)
+{
+    auto context = create_testing_context(64, 64);
+
+    GLuint texture_id;
+    glGenTextures(1, &texture_id);
+    glBindTexture(GL_TEXTURE_2D, texture_id);
+    u16 texture_data[] = { 0xF800, 0xC000, 0x8000, 0x07E0, 0x0600, 0x0400, 0x001F, 0x0018, 0x0010 };
+    glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
+    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, 3, 3, 0, GL_RGB, GL_UNSIGNED_SHORT_5_6_5, texture_data);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+
+    glEnable(GL_TEXTURE_2D);
+    glBegin(GL_QUADS);
+    glTexCoord2i(0, 0);
+    glVertex2i(-1, 1);
+    glTexCoord2i(0, 1);
+    glVertex2i(-1, -1);
+    glTexCoord2i(1, 1);
+    glVertex2i(1, -1);
+    glTexCoord2i(1, 0);
+    glVertex2i(1, 1);
+    glEnd();
+
+    EXPECT_EQ(glGetError(), 0u);
+
+    context->present();
+    expect_bitmap_equals_reference(context->frontbuffer(), "0006_test_rgb565_texture"sv);
+}

Tests/LibGL/reference-images/0006_test_rgb565_texture.qoi

@@ -3,6 +3,7 @@ set(SOURCES
     ContextParameter.cpp
     GLAPI.cpp
     GLContext.cpp
+    Image.cpp
     Lighting.cpp
     List.cpp
     Matrix.cpp

Userland/Libraries/LibGL/CMakeLists.txt

@@ -584,4 +584,28 @@ GLboolean GLContext::gl_is_enabled(GLenum capability)
     return parameter.value.boolean_value;
 }
 
+GPU::PackingSpecification GLContext::get_packing_specification(PackingType packing_type)
+{
+    // Make use of the fact that the GL_PACK_* and GL_UNPACK_* enum constants are in the exact same order
+    auto const offset = (packing_type == PackingType::Unpack) ? 0 : (GL_PACK_SWAP_BYTES - GL_UNPACK_SWAP_BYTES);
+    auto get_packing_value = [&](GLenum packing_parameter) -> GLint {
+        GLint value;
+        gl_get_integerv(packing_parameter + offset, &value);
+        return value;
+    };
+
+    // FIXME: add support for GL_UNPACK_SKIP_PIXELS, GL_UNPACK_SKIP_ROWS and GL_UNPACK_LSB_FIRST
+    GLint byte_alignment { get_packing_value(GL_UNPACK_ALIGNMENT) };
+    GLint swap_bytes { get_packing_value(GL_UNPACK_SWAP_BYTES) };
+    GLint depth_stride { get_packing_value(GL_UNPACK_IMAGE_HEIGHT) };
+    GLint row_stride { get_packing_value(GL_UNPACK_ROW_LENGTH) };
+
+    return {
+        .depth_stride = static_cast<u32>(depth_stride),
+        .row_stride = static_cast<u32>(row_stride),
+        .byte_alignment = static_cast<u8>(byte_alignment),
+        .component_bytes_order = swap_bytes == GL_TRUE ? GPU::ComponentBytesOrder::Reversed : GPU::ComponentBytesOrder::Normal,
+    };
+}
+
 }

Userland/Libraries/LibGL/ContextParameter.cpp

@@ -217,6 +217,7 @@ extern "C" {
 #define GL_COMPILE_AND_EXECUTE 0x1301
 
 // Type enums
+#define GL_BITMAP 0x1A00
 #define GL_BYTE 0x1400
 #define GL_UNSIGNED_BYTE 0x1401
 #define GL_SHORT 0x1402
@@ -228,11 +229,23 @@ extern "C" {
 #define GL_3_BYTES 0x1408
 #define GL_4_BYTES 0x1409
 #define GL_DOUBLE 0x140A
+#define GL_HALF_FLOAT 0x140B
+#define GL_UNSIGNED_BYTE_3_3_2 0x8032
+#define GL_UNSIGNED_SHORT_4_4_4_4 0x8033
+#define GL_UNSIGNED_SHORT_5_5_5_1 0x8034
+#define GL_UNSIGNED_INT_8_8_8_8 0x8035
+#define GL_UNSIGNED_INT_10_10_10_2 0x8036
+#define GL_UNSIGNED_BYTE_2_3_3_REV 0x8362
+#define GL_UNSIGNED_SHORT_5_6_5 0x8363
+#define GL_UNSIGNED_SHORT_5_6_5_REV 0x8364
+#define GL_UNSIGNED_SHORT_4_4_4_4_REV 0x8365
+#define GL_UNSIGNED_SHORT_1_5_5_5_REV 0x8366
+#define GL_UNSIGNED_INT_8_8_8_8_REV 0x8367
+#define GL_UNSIGNED_INT_2_10_10_10_REV 0x8368
 #define GL_BOOL 0x8B56
 
 // Format enums
 #define GL_COLOR_INDEX 0x1900
-#define GL_COLOR_INDEX8_EXT 0x80E5
 #define GL_STENCIL_INDEX 0x1901
 #define GL_DEPTH_COMPONENT 0x1902
 #define GL_RED 0x1903
@@ -244,21 +257,80 @@ extern "C" {
 #define GL_LUMINANCE 0x1909
 #define GL_LUMINANCE8 0x8040
 #define GL_LUMINANCE_ALPHA 0x190A
-#define GL_LUMINANCE8_ALPHA8 0x8045
+#define GL_R3_G3_B2 0x2A10
 #define GL_BGR 0x80E0
 #define GL_BGRA 0x80E1
-#define GL_BITMAP 0x1A00
-
+#define GL_ALPHA4 0x803B
+#define GL_ALPHA8 0x803C
+#define GL_ALPHA12 0x803D
+#define GL_ALPHA16 0x803E
+#define GL_LUMINANCE4 0x803F
 #define GL_LUMINANCE8 0x8040
+#define GL_LUMINANCE12 0x8041
+#define GL_LUMINANCE16 0x8042
+#define GL_LUMINANCE4_ALPHA4 0x8043
+#define GL_LUMINANCE6_ALPHA2 0x8044
+#define GL_LUMINANCE8_ALPHA8 0x8045
+#define GL_LUMINANCE12_ALPHA4 0x8046
+#define GL_LUMINANCE12_ALPHA12 0x8047
+#define GL_LUMINANCE16_ALPHA16 0x8048
+#define GL_INTENSITY 0x8049
+#define GL_INTENSITY4 0x804A
 #define GL_INTENSITY8 0x804B
-#define GL_R3_G3_B2 0x2A10
+#define GL_INTENSITY12 0x804C
+#define GL_INTENSITY16 0x804D
 #define GL_RGB4 0x804F
 #define GL_RGB5 0x8050
 #define GL_RGB8 0x8051
+#define GL_RGB10 0x8052
+#define GL_RGB12 0x8053
+#define GL_RGB16 0x8054
 #define GL_RGBA2 0x8055
 #define GL_RGBA4 0x8056
 #define GL_RGB5_A1 0x8057
 #define GL_RGBA8 0x8058
+#define GL_RGB10_A2 0x8059
+#define GL_RGBA12 0x805A
+#define GL_RGBA16 0x805B
+#define GL_COLOR_INDEX8_EXT 0x80E5
+#define GL_DEPTH_COMPONENT16 0x81A5
+#define GL_DEPTH_COMPONENT16_SGIX 0x81A5
+#define GL_DEPTH_COMPONENT24 0x81A6
+#define GL_DEPTH_COMPONENT24_SGIX 0x81A6
+#define GL_DEPTH_COMPONENT32 0x81A7
+#define GL_DEPTH_COMPONENT32_SGIX 0x81A7
+#define GL_RG 0x8227
+#define GL_COMPRESSED_ALPHA 0x84E9
+#define GL_COMPRESSED_ALPHA_ARB 0x84E9
+#define GL_COMPRESSED_LUMINANCE 0x84EA
+#define GL_COMPRESSED_LUMINANCE_ARB 0x84EA
+#define GL_COMPRESSED_LUMINANCE_ALPHA 0x84EB
+#define GL_COMPRESSED_LUMINANCE_ALPHA_ARB 0x84EB
+#define GL_COMPRESSED_INTENSITY 0x84EC
+#define GL_COMPRESSED_INTENSITY_ARB 0x84EC
+#define GL_COMPRESSED_RGB 0x84ED
+#define GL_COMPRESSED_RGB_ARB 0x84ED
+#define GL_COMPRESSED_RGBA 0x84EE
+#define GL_COMPRESSED_RGBA_ARB 0x84EE
+#define GL_DEPTH_STENCIL 0x84F9
+#define GL_DEPTH_STENCIL_EXT 0x84F9
+#define GL_DEPTH_STENCIL_NV 0x84F9
+#define GL_SRGB 0x8C40
+#define GL_SRGB_EXT 0x8C40
+#define GL_SRGB8 0x8C41
+#define GL_SRGB8_EXT 0x8C41
+#define GL_SRGB_ALPHA 0x8C42
+#define GL_SRGB_ALPHA_EXT 0x8C42
+#define GL_SRGB8_ALPHA8 0x8C43
+#define GL_SRGB8_ALPHA8_EXT 0x8C43
+#define GL_SLUMINANCE_ALPHA 0x8C44
+#define GL_SLUMINANCE_ALPHA_EXT 0x8C44
+#define GL_SLUMINANCE8_ALPHA8 0x8C45
+#define GL_SLUMINANCE8_ALPHA8_EXT 0x8C45
+#define GL_SLUMINANCE 0x8C46
+#define GL_SLUMINANCE_EXT 0x8C46
+#define GL_SLUMINANCE8 0x8C47
+#define GL_SLUMINANCE8_EXT 0x8C47
 
 // Lighting related defines
 #define GL_LIGHTING 0x0B50
@@ -313,21 +385,6 @@ extern "C" {
 #define GL_LINE 0x1B01
 #define GL_FILL 0x1B02
 
-// Source pixel data format
-#define GL_UNSIGNED_BYTE 0x1401
-#define GL_UNSIGNED_BYTE_3_3_2 0x8032
-#define GL_UNSIGNED_SHORT_4_4_4_4 0x8033
-#define GL_UNSIGNED_SHORT_5_5_5_1 0x8034
-#define GL_UNSIGNED_INT_8_8_8_8 0x8035
-#define GL_UNSIGNED_INT_10_10_10_2 0x8036
-#define GL_UNSIGNED_BYTE_2_3_3_REV 0x8362
-#define GL_UNSIGNED_SHORT_5_6_5 0x8363
-#define GL_UNSIGNED_SHORT_5_6_5_REV 0x8364
-#define GL_UNSIGNED_SHORT_4_4_4_4_REV 0x8365
-#define GL_UNSIGNED_SHORT_1_5_5_5_REV 0x8366
-#define GL_UNSIGNED_INT_8_8_8_8_REV 0x8367
-#define GL_UNSIGNED_INT_2_10_10_10_REV 0x8368
-
 // Stencil buffer operations
 #define GL_KEEP 0x1E00
 #define GL_REPLACE 0x1E01