src/render/software/SDL_render_sw.c

/*
  Simple DirectMedia Layer
  Copyright (C) 1997-2011 Sam Lantinga <slouken@libsdl.org>

  This software is provided 'as-is', without any express or implied
  warranty.  In no event will the authors be held liable for any damages
  arising from the use of this software.

  Permission is granted to anyone to use this software for any purpose,
  including commercial applications, and to alter it and redistribute it
  freely, subject to the following restrictions:

  1. The origin of this software must not be misrepresented; you must not
     claim that you wrote the original software. If you use this software
     in a product, an acknowledgment in the product documentation would be
     appreciated but is not required.
  2. Altered source versions must be plainly marked as such, and must not be
     misrepresented as being the original software.
  3. This notice may not be removed or altered from any source distribution.
*/
#include "SDL_config.h"

#if !SDL_RENDER_DISABLED

#include "../SDL_sysrender.h"

#include "SDL_draw.h"
#include "SDL_blendfillrect.h"
#include "SDL_blendline.h"
#include "SDL_blendpoint.h"
#include "SDL_drawline.h"
#include "SDL_drawpoint.h"


/* SDL surface based renderer implementation */

static SDL_Renderer *SW_CreateRenderer(SDL_Window * window, Uint32 flags);
static void SW_WindowEvent(SDL_Renderer * renderer,
                           const SDL_WindowEvent *event);
static int SW_CreateTexture(SDL_Renderer * renderer, SDL_Texture * texture);
static int SW_SetTextureColorMod(SDL_Renderer * renderer,
                                 SDL_Texture * texture);
static int SW_SetTextureAlphaMod(SDL_Renderer * renderer,
                                 SDL_Texture * texture);
static int SW_SetTextureBlendMode(SDL_Renderer * renderer,
                                  SDL_Texture * texture);
static int SW_UpdateTexture(SDL_Renderer * renderer, SDL_Texture * texture,
                            const SDL_Rect * rect, const void *pixels,
                            int pitch);
static int SW_LockTexture(SDL_Renderer * renderer, SDL_Texture * texture,
                          const SDL_Rect * rect, void **pixels, int *pitch);
static void SW_UnlockTexture(SDL_Renderer * renderer, SDL_Texture * texture);
static int SW_UpdateViewport(SDL_Renderer * renderer);
static int SW_RenderClear(SDL_Renderer * renderer);
static int SW_RenderDrawPoints(SDL_Renderer * renderer,
                               const SDL_Point * points, int count);
static int SW_RenderDrawLines(SDL_Renderer * renderer,
                              const SDL_Point * points, int count);
static int SW_RenderFillRects(SDL_Renderer * renderer,
                              const SDL_Rect * rects, int count);
static int SW_RenderCopy(SDL_Renderer * renderer, SDL_Texture * texture,
                         const SDL_Rect * srcrect, const SDL_Rect * dstrect);
static int SW_RenderReadPixels(SDL_Renderer * renderer, const SDL_Rect * rect,
                               Uint32 format, void * pixels, int pitch);
static void SW_RenderPresent(SDL_Renderer * renderer);
static void SW_DestroyTexture(SDL_Renderer * renderer, SDL_Texture * texture);
static void SW_DestroyRenderer(SDL_Renderer * renderer);


SDL_RenderDriver SW_RenderDriver = {
    SW_CreateRenderer,
    {
     "software",
     SDL_RENDERER_SOFTWARE,
     8,
     {
      SDL_PIXELFORMAT_RGB555,
      SDL_PIXELFORMAT_RGB565,
      SDL_PIXELFORMAT_RGB888,
      SDL_PIXELFORMAT_BGR888,
      SDL_PIXELFORMAT_ARGB8888,
      SDL_PIXELFORMAT_RGBA8888,
      SDL_PIXELFORMAT_ABGR8888,
      SDL_PIXELFORMAT_BGRA8888
     },
     0,
     0}
};

typedef struct
{
    SDL_Surface *surface;
} SW_RenderData;


static SDL_Surface *
SW_ActivateRenderer(SDL_Renderer * renderer)
{
    SW_RenderData *data = (SW_RenderData *) renderer->driverdata;

    if (!data->surface) {
        data->surface = SDL_GetWindowSurface(renderer->window);

        SW_UpdateViewport(renderer);
    }
    return data->surface;
}

SDL_Renderer *
SW_CreateRendererForSurface(SDL_Surface * surface)
{
    SDL_Renderer *renderer;
    SW_RenderData *data;

    if (!surface) {
        SDL_SetError("Can't create renderer for NULL surface");
        return NULL;
    }

    renderer = (SDL_Renderer *) SDL_calloc(1, sizeof(*renderer));
    if (!renderer) {
        SDL_OutOfMemory();
        return NULL;
    }

    data = (SW_RenderData *) SDL_calloc(1, sizeof(*data));
    if (!data) {
        SW_DestroyRenderer(renderer);
        SDL_OutOfMemory();
        return NULL;
    }
    data->surface = surface;

    renderer->WindowEvent = SW_WindowEvent;
    renderer->CreateTexture = SW_CreateTexture;
    renderer->SetTextureColorMod = SW_SetTextureColorMod;
    renderer->SetTextureAlphaMod = SW_SetTextureAlphaMod;
    renderer->SetTextureBlendMode = SW_SetTextureBlendMode;
    renderer->UpdateTexture = SW_UpdateTexture;
    renderer->LockTexture = SW_LockTexture;
    renderer->UnlockTexture = SW_UnlockTexture;
    renderer->UpdateViewport = SW_UpdateViewport;
    renderer->DestroyTexture = SW_DestroyTexture;
    renderer->RenderClear = SW_RenderClear;
    renderer->RenderDrawPoints = SW_RenderDrawPoints;
    renderer->RenderDrawLines = SW_RenderDrawLines;
    renderer->RenderFillRects = SW_RenderFillRects;
    renderer->RenderCopy = SW_RenderCopy;
    renderer->RenderReadPixels = SW_RenderReadPixels;
    renderer->RenderPresent = SW_RenderPresent;
    renderer->DestroyRenderer = SW_DestroyRenderer;
    renderer->info = SW_RenderDriver.info;
    renderer->driverdata = data;

    SW_ActivateRenderer(renderer);

    return renderer;
}

SDL_Renderer *
SW_CreateRenderer(SDL_Window * window, Uint32 flags)
{
    SDL_Surface *surface;

    surface = SDL_GetWindowSurface(window);
    if (!surface) {
        return NULL;
    }
    return SW_CreateRendererForSurface(surface);
}

static void
SW_WindowEvent(SDL_Renderer * renderer, const SDL_WindowEvent *event)
{
    SW_RenderData *data = (SW_RenderData *) renderer->driverdata;

    if (event->event == SDL_WINDOWEVENT_SIZE_CHANGED) {
        data->surface = NULL;
    }
}

static int
SW_CreateTexture(SDL_Renderer * renderer, SDL_Texture * texture)
{
    int bpp;
    Uint32 Rmask, Gmask, Bmask, Amask;

    if (!SDL_PixelFormatEnumToMasks
        (texture->format, &bpp, &Rmask, &Gmask, &Bmask, &Amask)) {
        SDL_SetError("Unknown texture format");
        return -1;
    }

    texture->driverdata =
        SDL_CreateRGBSurface(0, texture->w, texture->h, bpp, Rmask, Gmask,
                             Bmask, Amask);
    SDL_SetSurfaceColorMod(texture->driverdata, texture->r, texture->g,
                           texture->b);
    SDL_SetSurfaceAlphaMod(texture->driverdata, texture->a);
    SDL_SetSurfaceBlendMode(texture->driverdata, texture->blendMode);

    if (texture->access == SDL_TEXTUREACCESS_STATIC) {
        SDL_SetSurfaceRLE(texture->driverdata, 1);
    }

    if (!texture->driverdata) {
        return -1;
    }
    return 0;
}

static int
SW_SetTextureColorMod(SDL_Renderer * renderer, SDL_Texture * texture)
{
    SDL_Surface *surface = (SDL_Surface *) texture->driverdata;
    return SDL_SetSurfaceColorMod(surface, texture->r, texture->g,
                                  texture->b);
}

static int
SW_SetTextureAlphaMod(SDL_Renderer * renderer, SDL_Texture * texture)
{
    SDL_Surface *surface = (SDL_Surface *) texture->driverdata;
    return SDL_SetSurfaceAlphaMod(surface, texture->a);
}

static int
SW_SetTextureBlendMode(SDL_Renderer * renderer, SDL_Texture * texture)
{
    SDL_Surface *surface = (SDL_Surface *) texture->driverdata;
    return SDL_SetSurfaceBlendMode(surface, texture->blendMode);
}

static int
SW_UpdateTexture(SDL_Renderer * renderer, SDL_Texture * texture,
                 const SDL_Rect * rect, const void *pixels, int pitch)
{
    SDL_Surface *surface = (SDL_Surface *) texture->driverdata;
    Uint8 *src, *dst;
    int row;
    size_t length;

    src = (Uint8 *) pixels;
    dst = (Uint8 *) surface->pixels +
                        rect->y * surface->pitch +
                        rect->x * surface->format->BytesPerPixel;
    length = rect->w * surface->format->BytesPerPixel;
    for (row = 0; row < rect->h; ++row) {
        SDL_memcpy(dst, src, length);
        src += pitch;
        dst += surface->pitch;
    }
    return 0;
}

static int
SW_LockTexture(SDL_Renderer * renderer, SDL_Texture * texture,
               const SDL_Rect * rect, void **pixels, int *pitch)
{
    SDL_Surface *surface = (SDL_Surface *) texture->driverdata;

    *pixels =
        (void *) ((Uint8 *) surface->pixels + rect->y * surface->pitch +
                  rect->x * surface->format->BytesPerPixel);
    *pitch = surface->pitch;
    return 0;
}

static void
SW_UnlockTexture(SDL_Renderer * renderer, SDL_Texture * texture)
{
}

static int
SW_UpdateViewport(SDL_Renderer * renderer)
{
    SW_RenderData *data = (SW_RenderData *) renderer->driverdata;
    SDL_Surface *surface = data->surface;

    if (!surface) {
        /* We'll update the viewport after we recreate the surface */
        return 0;
    }

    if (!renderer->viewport.w && !renderer->viewport.h) {
        /* There may be no window, so update the viewport directly */
        renderer->viewport.w = surface->w;
        renderer->viewport.h = surface->h;
    }
    SDL_SetClipRect(data->surface, &renderer->viewport);
    return 0;
}

static int
SW_RenderClear(SDL_Renderer * renderer)
{
    SDL_Surface *surface = SW_ActivateRenderer(renderer);
    Uint32 color;
    SDL_Rect clip_rect;

    if (!surface) {
        return -1;
    }

    color = SDL_MapRGBA(surface->format,
                        renderer->r, renderer->g, renderer->b, renderer->a);

    /* By definition the clear ignores the clip rect */
    clip_rect = surface->clip_rect;
    SDL_SetClipRect(surface, NULL);
    SDL_FillRect(surface, NULL, color);
    SDL_SetClipRect(surface, &clip_rect);
    return 0;
}

static int
SW_RenderDrawPoints(SDL_Renderer * renderer, const SDL_Point * points,
                    int count)
{
    SDL_Surface *surface = SW_ActivateRenderer(renderer);
    SDL_Point *temp = NULL;
    int status;

    if (!surface) {
        return -1;
    }

    if (renderer->viewport.x || renderer->viewport.y) {
        int i;
        int x = renderer->viewport.x;
        int y = renderer->viewport.y;

        temp = SDL_stack_alloc(SDL_Point, count);
        for (i = 0; i < count; ++i) {
            temp[i].x = x + points[i].x;
            temp[i].y = y + points[i].x;
        }
        points = temp;
    }

    /* Draw the points! */
    if (renderer->blendMode == SDL_BLENDMODE_NONE) {
        Uint32 color = SDL_MapRGBA(surface->format,
                                   renderer->r, renderer->g, renderer->b,
                                   renderer->a);

        status = SDL_DrawPoints(surface, points, count, color);
    } else {
        status = SDL_BlendPoints(surface, points, count,
                                renderer->blendMode,
                                renderer->r, renderer->g, renderer->b,
                                renderer->a);
    }

    if (temp) {
        SDL_stack_free(temp);
    }
    return status;
}

static int
SW_RenderDrawLines(SDL_Renderer * renderer, const SDL_Point * points,
                   int count)
{
    SDL_Surface *surface = SW_ActivateRenderer(renderer);
    SDL_Point *temp = NULL;
    int status;

    if (!surface) {
        return -1;
    }

    if (renderer->viewport.x || renderer->viewport.y) {
        int i;
        int x = renderer->viewport.x;
        int y = renderer->viewport.y;

        temp = SDL_stack_alloc(SDL_Point, count);
        for (i = 0; i < count; ++i) {
            temp[i].x = x + points[i].x;
            temp[i].y = y + points[i].y;
        }
        points = temp;
    }

    /* Draw the lines! */
    if (renderer->blendMode == SDL_BLENDMODE_NONE) {
        Uint32 color = SDL_MapRGBA(surface->format,
                                   renderer->r, renderer->g, renderer->b,
                                   renderer->a);

        status = SDL_DrawLines(surface, points, count, color);
    } else {
        status = SDL_BlendLines(surface, points, count,
                                renderer->blendMode,
                                renderer->r, renderer->g, renderer->b,
                                renderer->a);
    }

    if (temp) {
        SDL_stack_free(temp);
    }
    return status;
}

static int
SW_RenderFillRects(SDL_Renderer * renderer, const SDL_Rect * rects, int count)
{
    SDL_Surface *surface = SW_ActivateRenderer(renderer);
    SDL_Rect *temp = NULL;
    int status;

    if (!surface) {
        return -1;
    }

    if (renderer->viewport.x || renderer->viewport.y) {
        int i;
        int x = renderer->viewport.x;
        int y = renderer->viewport.y;

        temp = SDL_stack_alloc(SDL_Rect, count);
        for (i = 0; i < count; ++i) {
            temp[i].x = x + rects[i].x;
            temp[i].y = y + rects[i].y;
            temp[i].w = rects[i].w;
            temp[i].h = rects[i].h;
        }
        rects = temp;
    }

    if (renderer->blendMode == SDL_BLENDMODE_NONE) {
        Uint32 color = SDL_MapRGBA(surface->format,
                                   renderer->r, renderer->g, renderer->b,
                                   renderer->a);
        status = SDL_FillRects(surface, rects, count, color);
    } else {
        status = SDL_BlendFillRects(surface, rects, count,
                                    renderer->blendMode,
                                    renderer->r, renderer->g, renderer->b,
                                    renderer->a);
    }

    if (temp) {
        SDL_stack_free(temp);
    }
    return status;
}

static int
SW_RenderCopy(SDL_Renderer * renderer, SDL_Texture * texture,
              const SDL_Rect * srcrect, const SDL_Rect * dstrect)
{
    SDL_Surface *surface = SW_ActivateRenderer(renderer);
    SDL_Surface *src = (SDL_Surface *) texture->driverdata;
    SDL_Rect final_rect = *dstrect;

    if (!surface) {
        return -1;
    }

    if (renderer->viewport.x || renderer->viewport.y) {
        final_rect.x += renderer->viewport.x;
        final_rect.y += renderer->viewport.y;
    }
    if ( srcrect->w == final_rect.w && srcrect->h == final_rect.h ) {
        return SDL_BlitSurface(src, srcrect, surface, &final_rect);
    } else {
        return SDL_BlitScaled(src, srcrect, surface, &final_rect);
    }
}

static int
SW_RenderReadPixels(SDL_Renderer * renderer, const SDL_Rect * rect,
                    Uint32 format, void * pixels, int pitch)
{
    SDL_Surface *surface = SW_ActivateRenderer(renderer);
    Uint32 src_format;
    void *src_pixels;
    SDL_Rect final_rect;

    if (!surface) {
        return -1;
    }

    if (renderer->viewport.x || renderer->viewport.y) {
        final_rect.x = renderer->viewport.x + rect->x;
        final_rect.y = renderer->viewport.y + rect->y;
        final_rect.w = rect->w;
        final_rect.h = rect->h;
        rect = &final_rect;
    }

    if (rect->x < 0 || rect->x+rect->w > surface->w ||
        rect->y < 0 || rect->y+rect->h > surface->h) {
        SDL_SetError("Tried to read outside of surface bounds");
        return -1;
    }

    src_format = surface->format->format;
    src_pixels = (void*)((Uint8 *) surface->pixels +
                    rect->y * surface->pitch +
                    rect->x * surface->format->BytesPerPixel);

    return SDL_ConvertPixels(rect->w, rect->h,
                             src_format, src_pixels, surface->pitch,
                             format, pixels, pitch);
}

static void
SW_RenderPresent(SDL_Renderer * renderer)
{
    SDL_Window *window = renderer->window;

    if (window) {
        SDL_UpdateWindowSurface(window);
    }
}

static void
SW_DestroyTexture(SDL_Renderer * renderer, SDL_Texture * texture)
{
    SDL_Surface *surface = (SDL_Surface *) texture->driverdata;

    SDL_FreeSurface(surface);
}

static void
SW_DestroyRenderer(SDL_Renderer * renderer)
{
    SW_RenderData *data = (SW_RenderData *) renderer->driverdata;

    if (data) {
        SDL_free(data);
    }
    SDL_free(renderer);
}

#endif /* !SDL_RENDER_DISABLED */

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