src/video/uikit/SDL_uikitopengles.m

/*
  Simple DirectMedia Layer
  Copyright (C) 1997-2014 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_internal.h"

#if SDL_VIDEO_DRIVER_UIKIT

#include "SDL_uikitopengles.h"
#include "SDL_uikitopenglview.h"
#include "SDL_uikitappdelegate.h"
#include "SDL_uikitmodes.h"
#include "SDL_uikitwindow.h"
#include "../SDL_sysvideo.h"
#include "../../events/SDL_keyboard_c.h"
#include "../../events/SDL_mouse_c.h"
#include "../../power/uikit/SDL_syspower.h"
#include "SDL_loadso.h"
#include <dlfcn.h>

static int UIKit_GL_Initialize(_THIS);

void *
UIKit_GL_GetProcAddress(_THIS, const char *proc)
{
    /* Look through all SO's for the proc symbol.  Here's why:
       -Looking for the path to the OpenGL Library seems not to work in the iPhone Simulator.
       -We don't know that the path won't change in the future.
    */
    return dlsym(RTLD_DEFAULT, proc);
}

/*
    note that SDL_GL_Delete context makes it current without passing the window
*/
int
UIKit_GL_MakeCurrent(_THIS, SDL_Window * window, SDL_GLContext context)
{
    @autoreleasepool {
        [EAGLContext setCurrentContext:(__bridge EAGLContext *)context];
    }
    return 0;
}

void UIKit_GL_GetDrawableSize(_THIS, SDL_Window * window, int * w, int * h)
{
    @autoreleasepool {
        SDL_WindowData *data = (__bridge SDL_WindowData *)window->driverdata;

        if (w) {
            *w = data.view.backingWidth;
        }
        if (h) {
            *h = data.view.backingHeight;
        }
    }
}


int
UIKit_GL_LoadLibrary(_THIS, const char *path)
{
    /*
        shouldn't be passing a path into this function
        why?  Because we've already loaded the library
        and because the SDK forbids loading an external SO
    */
    if (path != NULL) {
        return SDL_SetError("iPhone GL Load Library just here for compatibility");
    }
    return 0;
}

void UIKit_GL_SwapWindow(_THIS, SDL_Window * window)
{
    @autoreleasepool {
        SDL_WindowData *data = (__bridge SDL_WindowData *)window->driverdata;

#if SDL_POWER_UIKIT
        /* Check once a frame to see if we should turn off the battery monitor. */
        SDL_UIKit_UpdateBatteryMonitoring();
#endif

        if (data.view == nil) {
            return;
        }
        [data.view swapBuffers];

        /* You need to pump events in order for the OS to make changes visible.
           We don't pump events here because we don't want iOS application events
           (low memory, terminate, etc.) to happen inside low level rendering.
         */
    }
}

SDL_GLContext
UIKit_GL_CreateContext(_THIS, SDL_Window * window)
{
    @autoreleasepool {
        SDL_uikitopenglview *view;
        SDL_WindowData *data = (__bridge SDL_WindowData *) window->driverdata;
        UIWindow *uiwindow = data.uiwindow;
        CGRect frame = UIKit_ComputeViewFrame(window, uiwindow.screen);
        EAGLSharegroup *share_group = nil;
        CGFloat scale = 1.0;

        if (window->flags & SDL_WINDOW_ALLOW_HIGHDPI) {
            /* Set the scale to the natural scale factor of the screen - the backing
               dimensions of the OpenGL view will match the pixel dimensions of the
               screen rather than the dimensions in points.
             */
            scale = uiwindow.screen.scale;
        }

        if (_this->gl_config.share_with_current_context) {
            SDL_uikitopenglview *view = (__bridge SDL_uikitopenglview *) SDL_GL_GetCurrentContext();
            share_group = [view.context sharegroup];
        }

        /* construct our view, passing in SDL's OpenGL configuration data */
        view = [[SDL_uikitopenglview alloc] initWithFrame: frame
                                                    scale: scale
                                            retainBacking: _this->gl_config.retained_backing
                                                    rBits: _this->gl_config.red_size
                                                    gBits: _this->gl_config.green_size
                                                    bBits: _this->gl_config.blue_size
                                                    aBits: _this->gl_config.alpha_size
                                                depthBits: _this->gl_config.depth_size
                                              stencilBits: _this->gl_config.stencil_size
                                                     sRGB: _this->gl_config.framebuffer_srgb_capable
                                             majorVersion: _this->gl_config.major_version
                                               shareGroup: share_group];
        if (!view) {
            return NULL;
        }

        data.view = view;
        view.viewcontroller = data.viewcontroller;
        if (view.viewcontroller != nil) {
            view.viewcontroller.view = view;
        }
        [uiwindow addSubview: view];

        /* The view controller needs to be the root in order to control rotation on iOS 6.0 */
        if (uiwindow.rootViewController == nil) {
            uiwindow.rootViewController = view.viewcontroller;
        }

        EAGLContext *context = view.context;
        if (UIKit_GL_MakeCurrent(_this, window, (__bridge SDL_GLContext) context) < 0) {
            UIKit_GL_DeleteContext(_this, (SDL_GLContext) CFBridgingRetain(context));
            return NULL;
        }

        /* Make this window the current mouse focus for touch input */
        if (uiwindow.screen == [UIScreen mainScreen]) {
            SDL_SetMouseFocus(window);
            SDL_SetKeyboardFocus(window);
        }

        return (SDL_GLContext) CFBridgingRetain(context);
    }
}

void
UIKit_GL_DeleteContext(_THIS, SDL_GLContext context)
{
    @autoreleasepool {
        SDL_Window *window;
        EAGLContext *eaglcontext = (EAGLContext *) CFBridgingRelease(context);

        /* Find the view associated with this context */
        for (window = _this->windows; window; window = window->next) {
            SDL_WindowData *data = (__bridge SDL_WindowData *) window->driverdata;
            SDL_uikitopenglview *view = data.view;
            if (view.context == eaglcontext) {
                /* the delegate has retained the view, this will release him */
                if (view.viewcontroller) {
                    UIWindow *uiwindow = (UIWindow *)view.superview;
                    if (uiwindow.rootViewController == view.viewcontroller) {
                        uiwindow.rootViewController = nil;
                    }
                    view.viewcontroller.view = nil;
                    view.viewcontroller = nil;
                }
                [view removeFromSuperview];

                data.view = nil;
                return;
            }
        }
    }
}

#endif /* SDL_VIDEO_DRIVER_UIKIT */

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