90 lines
2.6 KiB
C++
90 lines
2.6 KiB
C++
#include "DisplaySDL.hpp"
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#include <stdexcept>
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DisplaySDL::DisplaySDL(int w, int h, uint32_t fgColor, uint32_t bgColor) {
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// Create SDL Window
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mpWindow = SDL_CreateWindow(
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"ChocoChip-8",
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SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED,
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w, h,
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0
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);
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if(mpWindow == NULL) {
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throw std::runtime_error(SDL_GetError());
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}
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// Convert our foreground/background colors to the format expected by SDL
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SDL_PixelFormat *fmt = SDL_AllocFormat(SDL_GetWindowPixelFormat(mpWindow));
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mFgColor = SDL_MapRGB(
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fmt,
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(fgColor & 0x00FF0000) >> 16,
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(fgColor & 0x0000FF00) >> 8,
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(fgColor & 0x000000FF)
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);
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mBgColor = SDL_MapRGB(
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fmt,
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(bgColor & 0x00FF0000) >> 16,
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(bgColor & 0x0000FF00) >> 8,
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(bgColor & 0x000000FF)
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);
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SDL_FreeFormat(fmt);
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};
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DisplaySDL::~DisplaySDL() {
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SDL_DestroyWindow(mpWindow);
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}
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void DisplaySDL::updateWindow() const {
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if(miTopDirtyScanline > miBottomDirtyScanline) {
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// No changes since the last update
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return;
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}
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SDL_Surface *pSurface = SDL_GetWindowSurface(mpWindow);
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SDL_LockSurface(pSurface);
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int fx, fy; // ChocoChip8 Framebuffer coordinates
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int sx, sy; // SDL Surface coordinates
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int lx, ly; // Last-used ChocoChip8 Framebuffer coordinates
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Uint32 lc; // Last-used SDL color
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// Fill the entire SDL surface, one pixel at a time
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lx = -1;
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ly = -1;
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for(sy = 0; sy < pSurface->h; sy++) {
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// Map SDL surface coordinates to Chocochip8 Framebuffer coordinates
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fy = sy * (double(chocochip8::gcHeight) / pSurface->h);
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if(fy < miTopDirtyScanline || miBottomDirtyScanline < fy) {
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// Skip scanlines that haven't changed since the last update
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continue;
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}
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for(sx = 0; sx < pSurface->w; sx++) {
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fx = sx * (double(chocochip8::gcWidth) / pSurface->w);
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// Reuse color if this screen pixel maps to the same ChocoChip8 pixel as the last
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if(fx != lx || fy != ly) {
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lx = fx;
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ly = ly;
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// Read Chocochip8 Framebuffer and choose appropriate color,
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// note that the MSB of an scanline's bitset is the leftmost pixel.
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lc = (mpFramebuffer->at(fy)[(chocochip8::gcWidth - 1) - fx] ? mFgColor : mBgColor);
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}
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// Convert (x, y) indexes into SDL Surface pixel array index
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Uint32 *pPixel = static_cast<Uint32*>(static_cast<void*>(
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static_cast<char*>(pSurface->pixels)
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+ sy * pSurface->pitch
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+ sx * pSurface->format->BytesPerPixel
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));
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*pPixel = lc;
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}
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}
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miTopDirtyScanline = chocochip8::gcHeight - 1;
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miBottomDirtyScanline = 0;
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SDL_UnlockSurface(pSurface);
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SDL_UpdateWindowSurface(mpWindow);
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}
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