feat(gfx): enhance Bitmap class with palette management and metadata support
- Added methods for applying palettes based on metadata, allowing for flexible palette handling in different bitmap types. - Introduced a new BitmapMetadata struct to track source format and palette requirements. - Enhanced ApplyStoredPalette and SetPaletteWithTransparent methods for improved palette application and transparency handling. - Updated SDL surface pixel management with a new UpdateSurfacePixels method for better pixel data handling. Benefits: - Improves the rendering capabilities of the Bitmap class by supporting various palette formats. - Enhances user experience with more intuitive palette management in graphics operations.
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scawful
@@ -249,6 +249,22 @@ void Bitmap::UpdateTexture() {
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/**
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* @brief Apply the stored palette to the SDL surface
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*
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* This method applies the palette_ member to the SDL surface's palette.
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*
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* IMPORTANT: Transparency handling
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* - ROM palette data does NOT have transparency flags set
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* - Transparency is only applied if explicitly marked (via set_transparent)
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* - For SNES rendering, use SetPaletteWithTransparent which creates
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* transparent color 0 automatically
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* - This method preserves the transparency state of each color
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*
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* Color format notes:
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* - SnesColor.rgb() returns 0-255 values stored in ImVec4 (unconventional!)
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* - We cast these directly to Uint8 for SDL
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*/
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void Bitmap::ApplyStoredPalette() {
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if (surface_ == nullptr) {
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return; // Can't apply without surface
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@@ -273,12 +289,16 @@ void Bitmap::ApplyStoredPalette() {
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// Apply all palette colors from the SnesPalette
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for (size_t i = 0; i < palette_.size() && i < 256; ++i) {
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const auto& pal_color = palette_[i];
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// NOTE: rgb() stores 0-255 values directly in ImVec4 (unconventional but intentional)
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sdl_palette->colors[i].r = static_cast<Uint8>(pal_color.rgb().x);
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sdl_palette->colors[i].g = static_cast<Uint8>(pal_color.rgb().y);
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sdl_palette->colors[i].b = static_cast<Uint8>(pal_color.rgb().z);
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// CRITICAL: Transparency for color 0 of each sub-palette
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// Get RGB values - stored as 0-255 in ImVec4 (unconventional!)
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ImVec4 rgb_255 = pal_color.rgb();
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sdl_palette->colors[i].r = static_cast<Uint8>(rgb_255.x);
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sdl_palette->colors[i].g = static_cast<Uint8>(rgb_255.y);
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sdl_palette->colors[i].b = static_cast<Uint8>(rgb_255.z);
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// Only apply transparency if explicitly set
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// (ROM data won't have this set; transparency is added during rendering)
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if (pal_color.is_transparent()) {
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sdl_palette->colors[i].a = 0; // Fully transparent
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} else {
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@@ -300,9 +320,67 @@ void Bitmap::SetPalette(const SnesPalette &palette) {
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modified_ = true;
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}
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/**
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* @brief Apply palette using metadata-driven strategy
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*
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* Uses bitmap metadata to determine the appropriate palette application method:
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* - palette_format == 0: Full palette (SetPalette)
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* - palette_format == 1: Sub-palette with transparent color 0 (SetPaletteWithTransparent)
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*
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* This ensures correct rendering for different bitmap types:
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* - 3BPP graphics sheets → sub-palette with transparent
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* - 4BPP full palettes → full palette
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* - Mode 7 graphics → full palette
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*
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* @param palette Source palette to apply
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* @param sub_palette_index Index within palette for sub-palette extraction (default 0)
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*/
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void Bitmap::ApplyPaletteByMetadata(const SnesPalette& palette, int sub_palette_index) {
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if (metadata_.palette_format == 1) {
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// Sub-palette: need transparent black + 7 colors from palette
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// Common for 3BPP graphics sheets (title screen, etc.)
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SetPaletteWithTransparent(palette, sub_palette_index, 7);
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} else {
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// Full palette application
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// Used for 4BPP, Mode 7, and other full-color formats
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SetPalette(palette);
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}
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}
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/**
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* @brief Apply a sub-palette with automatic transparency for SNES rendering
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*
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* This method extracts a sub-palette from a larger palette and applies it
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* to the SDL surface with proper SNES transparency handling.
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*
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* SNES Transparency Model:
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* - The SNES hardware automatically treats palette index 0 as transparent
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* - This is a hardware feature, not stored in ROM data
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* - This method creates a transparent color 0 for proper SNES emulation
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*
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* Usage:
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* - Extract 8-color sub-palette from position 'index' in source palette
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* - Color 0: Always set to transparent black (0,0,0,0)
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* - Colors 1-7: Taken from palette[index] through palette[index+6]
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* - If palette has fewer than 7 colors, fills with opaque black
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*
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* Example:
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* palette has colors [c0, c1, c2, c3, c4, c5, c6, c7, c8, ...]
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* SetPaletteWithTransparent(palette, 0, 7) creates:
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* [transparent_black, c0, c1, c2, c3, c4, c5, c6]
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*
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* IMPORTANT: Source palette data is NOT modified
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* - The full palette is stored in palette_ member for reference
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* - Only the SDL surface palette is updated with the 8-color subset
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* - This allows proper palette editing while maintaining SNES rendering
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*
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* @param palette Source palette (can be 7, 8, 64, 128, or 256 colors)
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* @param index Start index in source palette (0-based)
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* @param length Number of colors to extract (default 7, max 7)
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*/
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void Bitmap::SetPaletteWithTransparent(const SnesPalette &palette, size_t index,
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int length) {
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// Store palette even if surface isn't ready yet
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// Store the full palette for reference (not modified)
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palette_ = palette;
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// If surface isn't created yet, just store the palette for later
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@@ -310,54 +388,52 @@ void Bitmap::SetPaletteWithTransparent(const SnesPalette &palette, size_t index,
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return; // Palette will be applied when surface is created
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}
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// CRITICAL FIX: Use index directly as palette slot, not index * 7
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// For 8-color palettes, index should be 0-7, not 0-49
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// Validate parameters
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if (index >= palette.size()) {
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throw std::invalid_argument("Invalid palette index");
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}
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if (length < 0 || length > 8) {
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throw std::invalid_argument("Invalid palette length (must be 0-8 for 8-color palettes)");
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if (length < 0 || length > 7) {
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throw std::invalid_argument("Invalid palette length (must be 0-7 for SNES palettes)");
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}
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if (index + length > palette.size()) {
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throw std::invalid_argument("Palette index + length exceeds size");
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}
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// Extract 8-color sub-palette starting at the specified index
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// This correctly handles both 256-color overworld palettes and smaller palettes
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// Build 8-color SNES sub-palette
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std::vector<ImVec4> colors;
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// Always start with transparent color (index 0)
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colors.push_back(ImVec4(0, 0, 0, 0));
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// Color 0: Transparent (SNES hardware requirement)
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colors.push_back(ImVec4(0, 0, 0, 0)); // Transparent black
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// Extract up to 7 colors from the palette starting at index
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// Colors 1-7: Extract from source palette
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// NOTE: palette[i].rgb() returns 0-255 values in ImVec4 (unconventional!)
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for (size_t i = 0; i < 7 && (index + i) < palette.size(); ++i) {
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auto &pal_color = palette[index + i];
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colors.push_back(pal_color.rgb());
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const auto &pal_color = palette[index + i];
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ImVec4 rgb_255 = pal_color.rgb(); // 0-255 range (unconventional storage)
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// Convert to standard ImVec4 0-1 range for SDL
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colors.push_back(ImVec4(rgb_255.x / 255.0f, rgb_255.y / 255.0f,
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rgb_255.z / 255.0f, 1.0f)); // Always opaque
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}
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// Ensure we have exactly 8 colors (transparent + 7 data colors)
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// Ensure we have exactly 8 colors
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while (colors.size() < 8) {
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colors.push_back(ImVec4(0, 0, 0, 1.0f)); // Fill with black if needed
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colors.push_back(ImVec4(0, 0, 0, 1.0f)); // Fill with opaque black
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}
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// CRITICAL FIX: Keep the original complete palette in palette_ member
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// Only update the SDL surface palette for display purposes
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// This prevents breaking other editors that expect the complete palette
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if (palette_.size() != palette.size()) {
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palette_ = palette; // Store complete palette
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InvalidatePaletteCache(); // Update cache with complete palette
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}
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// Update palette cache with full palette (for color lookup)
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InvalidatePaletteCache();
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// Apply the 8-color sub-palette to SDL surface for display
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// Apply the 8-color SNES sub-palette to SDL surface
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SDL_UnlockSurface(surface_);
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for (int color_index = 0; color_index < 8 && color_index < static_cast<int>(colors.size()); ++color_index) {
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if (color_index < surface_->format->palette->ncolors) {
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surface_->format->palette->colors[color_index].r = static_cast<Uint8>(colors[color_index].x * 255);
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surface_->format->palette->colors[color_index].g = static_cast<Uint8>(colors[color_index].y * 255);
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surface_->format->palette->colors[color_index].b = static_cast<Uint8>(colors[color_index].z * 255);
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surface_->format->palette->colors[color_index].a = static_cast<Uint8>(colors[color_index].w * 255);
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surface_->format->palette->colors[color_index].r = static_cast<Uint8>(colors[color_index].x * 255.0f);
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surface_->format->palette->colors[color_index].g = static_cast<Uint8>(colors[color_index].y * 255.0f);
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surface_->format->palette->colors[color_index].b = static_cast<Uint8>(colors[color_index].z * 255.0f);
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surface_->format->palette->colors[color_index].a = static_cast<Uint8>(colors[color_index].w * 255.0f);
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}
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}
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SDL_LockSurface(surface_);
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@@ -167,6 +167,12 @@ class Bitmap {
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void SetPaletteWithTransparent(const SnesPalette &palette, size_t index,
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int length = 7);
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/**
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* @brief Apply palette using metadata-driven strategy
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* Chooses between SetPalette and SetPaletteWithTransparent based on metadata
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*/
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void ApplyPaletteByMetadata(const SnesPalette& palette, int sub_palette_index = 0);
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/**
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* @brief Apply the stored palette to the surface (internal helper)
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*/
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@@ -248,8 +254,25 @@ class Bitmap {
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void Get16x16Tile(int tile_x, int tile_y, std::vector<uint8_t> &tile_data,
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int &tile_data_offset);
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/**
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* @brief Metadata for tracking bitmap source format and palette requirements
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*/
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struct BitmapMetadata {
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int source_bpp = 8; // Original bits per pixel (3, 4, 8)
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int palette_format = 0; // 0=full palette, 1=sub-palette with transparent
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std::string source_type; // "graphics_sheet", "tilemap", "screen_buffer", "mode7"
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int palette_colors = 256; // Expected palette size
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BitmapMetadata() = default;
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BitmapMetadata(int bpp, int format, const std::string& type, int colors = 256)
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: source_bpp(bpp), palette_format(format), source_type(type), palette_colors(colors) {}
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};
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const SnesPalette &palette() const { return palette_; }
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SnesPalette *mutable_palette() { return &palette_; }
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BitmapMetadata& metadata() { return metadata_; }
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const BitmapMetadata& metadata() const { return metadata_; }
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int width() const { return width_; }
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int height() const { return height_; }
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int depth() const { return depth_; }
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@@ -285,6 +308,9 @@ class Bitmap {
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// Palette for the bitmap
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gfx::SnesPalette palette_;
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// Metadata for tracking source format and palette requirements
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BitmapMetadata metadata_;
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// Data for the bitmap
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std::vector<uint8_t> data_;
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