#include "screen.h" #include #include #include #include "events.h" #include "icon.h" #include "options.h" #include "video_buffer.h" #include "util/log.h" #define DISPLAY_MARGINS 96 #define DOWNCAST(SINK) container_of(SINK, struct sc_screen, frame_sink) static inline struct sc_size get_rotated_size(struct sc_size size, int rotation) { struct sc_size rotated_size; if (rotation & 1) { rotated_size.width = size.height; rotated_size.height = size.width; } else { rotated_size.width = size.width; rotated_size.height = size.height; } return rotated_size; } // get the window size in a struct sc_size static struct sc_size get_window_size(const struct sc_screen *screen) { int width; int height; SDL_GetWindowSize(screen->window, &width, &height); struct sc_size size; size.width = width; size.height = height; return size; } static struct sc_point get_window_position(const struct sc_screen *screen) { int x; int y; SDL_GetWindowPosition(screen->window, &x, &y); struct sc_point point; point.x = x; point.y = y; return point; } // set the window size to be applied when fullscreen is disabled static void set_window_size(struct sc_screen *screen, struct sc_size new_size) { assert(!screen->fullscreen); assert(!screen->maximized); SDL_SetWindowSize(screen->window, new_size.width, new_size.height); } // get the preferred display bounds (i.e. the screen bounds with some margins) static bool get_preferred_display_bounds(struct sc_size *bounds) { SDL_Rect rect; if (SDL_GetDisplayUsableBounds(0, &rect)) { LOGW("Could not get display usable bounds: %s", SDL_GetError()); return false; } bounds->width = MAX(0, rect.w - DISPLAY_MARGINS); bounds->height = MAX(0, rect.h - DISPLAY_MARGINS); return true; } static bool is_optimal_size(struct sc_size current_size, struct sc_size content_size) { // The size is optimal if we can recompute one dimension of the current // size from the other return current_size.height == current_size.width * content_size.height / content_size.width || current_size.width == current_size.height * content_size.width / content_size.height; } // return the optimal size of the window, with the following constraints: // - it attempts to keep at least one dimension of the current_size (i.e. it // crops the black borders) // - it keeps the aspect ratio // - it scales down to make it fit in the display_size static struct sc_size get_optimal_size(struct sc_size current_size, struct sc_size content_size, bool within_display_bounds) { if (content_size.width == 0 || content_size.height == 0) { // avoid division by 0 return current_size; } struct sc_size window_size; struct sc_size display_size; if (!within_display_bounds || !get_preferred_display_bounds(&display_size)) { // do not constraint the size window_size = current_size; } else { window_size.width = MIN(current_size.width, display_size.width); window_size.height = MIN(current_size.height, display_size.height); } if (is_optimal_size(window_size, content_size)) { return window_size; } bool keep_width = content_size.width * window_size.height > content_size.height * window_size.width; if (keep_width) { // remove black borders on top and bottom window_size.height = content_size.height * window_size.width / content_size.width; } else { // remove black borders on left and right (or none at all if it already // fits) window_size.width = content_size.width * window_size.height / content_size.height; } return window_size; } // initially, there is no current size, so use the frame size as current size // req_width and req_height, if not 0, are the sizes requested by the user static inline struct sc_size get_initial_optimal_size(struct sc_size content_size, uint16_t req_width, uint16_t req_height) { struct sc_size window_size; if (!req_width && !req_height) { window_size = get_optimal_size(content_size, content_size, true); } else { if (req_width) { window_size.width = req_width; } else { // compute from the requested height window_size.width = (uint32_t) req_height * content_size.width / content_size.height; } if (req_height) { window_size.height = req_height; } else { // compute from the requested width window_size.height = (uint32_t) req_width * content_size.height / content_size.width; } } return window_size; } static inline void sc_screen_capture_mouse(struct sc_screen *screen, bool capture) { if (SDL_SetRelativeMouseMode(capture)) { LOGE("Could not set relative mouse mode to %s: %s", capture ? "true" : "false", SDL_GetError()); return; } screen->mouse_captured = capture; } static void sc_screen_update_content_rect(struct sc_screen *screen) { int dw; int dh; SDL_GL_GetDrawableSize(screen->window, &dw, &dh); struct sc_size content_size = screen->content_size; // The drawable size is the window size * the HiDPI scale struct sc_size drawable_size = {dw, dh}; SDL_Rect *rect = &screen->rect; if (is_optimal_size(drawable_size, content_size)) { rect->x = 0; rect->y = 0; rect->w = drawable_size.width; rect->h = drawable_size.height; return; } bool keep_width = content_size.width * drawable_size.height > content_size.height * drawable_size.width; if (keep_width) { rect->x = 0; rect->w = drawable_size.width; rect->h = drawable_size.width * content_size.height / content_size.width; rect->y = (drawable_size.height - rect->h) / 2; } else { rect->y = 0; rect->h = drawable_size.height; rect->w = drawable_size.height * content_size.width / content_size.height; rect->x = (drawable_size.width - rect->w) / 2; } } static inline SDL_Texture * create_texture(struct sc_screen *screen) { SDL_Renderer *renderer = screen->renderer; struct sc_size size = screen->frame_size; SDL_Texture *texture = SDL_CreateTexture(renderer, SDL_PIXELFORMAT_YV12, SDL_TEXTUREACCESS_STREAMING, size.width, size.height); if (!texture) { return NULL; } if (screen->mipmaps) { struct sc_opengl *gl = &screen->gl; SDL_GL_BindTexture(texture, NULL, NULL); // Enable trilinear filtering for downscaling gl->TexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR); gl->TexParameterf(GL_TEXTURE_2D, GL_TEXTURE_LOD_BIAS, -1.f); SDL_GL_UnbindTexture(texture); } return texture; } // render the texture to the renderer // // Set the update_content_rect flag if the window or content size may have // changed, so that the content rectangle is recomputed static void sc_screen_render(struct sc_screen *screen, bool update_content_rect) { if (update_content_rect) { sc_screen_update_content_rect(screen); } SDL_RenderClear(screen->renderer); if (screen->rotation == 0) { SDL_RenderCopy(screen->renderer, screen->texture, NULL, &screen->rect); } else { // rotation in RenderCopyEx() is clockwise, while screen->rotation is // counterclockwise (to be consistent with --lock-video-orientation) int cw_rotation = (4 - screen->rotation) % 4; double angle = 90 * cw_rotation; SDL_Rect *dstrect = NULL; SDL_Rect rect; if (screen->rotation & 1) { rect.x = screen->rect.x + (screen->rect.w - screen->rect.h) / 2; rect.y = screen->rect.y + (screen->rect.h - screen->rect.w) / 2; rect.w = screen->rect.h; rect.h = screen->rect.w; dstrect = ▭ } else { assert(screen->rotation == 2); dstrect = &screen->rect; } SDL_RenderCopyEx(screen->renderer, screen->texture, NULL, dstrect, angle, NULL, 0); } SDL_RenderPresent(screen->renderer); } #if defined(__APPLE__) || defined(__WINDOWS__) # define CONTINUOUS_RESIZING_WORKAROUND #endif #ifdef CONTINUOUS_RESIZING_WORKAROUND // On Windows and MacOS, resizing blocks the event loop, so resizing events are // not triggered. As a workaround, handle them in an event handler. // // // static int event_watcher(void *data, SDL_Event *event) { struct sc_screen *screen = data; if (event->type == SDL_WINDOWEVENT && event->window.event == SDL_WINDOWEVENT_RESIZED) { // In practice, it seems to always be called from the same thread in // that specific case. Anyway, it's just a workaround. sc_screen_render(screen, true); } return 0; } #endif static bool sc_screen_frame_sink_open(struct sc_frame_sink *sink) { struct sc_screen *screen = DOWNCAST(sink); (void) screen; #ifndef NDEBUG screen->open = true; #endif // nothing to do, the screen is already open on the main thread return true; } static void sc_screen_frame_sink_close(struct sc_frame_sink *sink) { struct sc_screen *screen = DOWNCAST(sink); (void) screen; #ifndef NDEBUG screen->open = false; #endif // nothing to do, the screen lifecycle is not managed by the frame producer } static bool sc_screen_frame_sink_push(struct sc_frame_sink *sink, const AVFrame *frame) { struct sc_screen *screen = DOWNCAST(sink); return sc_video_buffer_push(&screen->vb, frame); } static void sc_video_buffer_on_new_frame(struct sc_video_buffer *vb, bool previous_skipped, void *userdata) { (void) vb; struct sc_screen *screen = userdata; // event_failed implies previous_skipped (the previous frame may not have // been consumed if the event was not sent) assert(!screen->event_failed || previous_skipped); bool need_new_event; if (previous_skipped) { fps_counter_add_skipped_frame(&screen->fps_counter); // The EVENT_NEW_FRAME triggered for the previous frame will consume // this new frame instead, unless the previous event failed need_new_event = screen->event_failed; } else { need_new_event = true; } if (need_new_event) { static SDL_Event new_frame_event = { .type = EVENT_NEW_FRAME, }; // Post the event on the UI thread int ret = SDL_PushEvent(&new_frame_event); if (ret < 0) { LOGW("Could not post new frame event: %s", SDL_GetError()); screen->event_failed = true; } else { screen->event_failed = false; } } } bool sc_screen_init(struct sc_screen *screen, const struct sc_screen_params *params) { screen->resize_pending = false; screen->has_frame = false; screen->fullscreen = false; screen->maximized = false; screen->event_failed = false; screen->mouse_captured = false; screen->mouse_capture_key_pressed = 0; static const struct sc_video_buffer_callbacks cbs = { .on_new_frame = sc_video_buffer_on_new_frame, }; bool ok = sc_video_buffer_init(&screen->vb, params->buffering_time, &cbs, screen); if (!ok) { return false; } ok = sc_video_buffer_start(&screen->vb); if (!ok) { goto error_destroy_video_buffer; } if (!fps_counter_init(&screen->fps_counter)) { goto error_stop_and_join_video_buffer; } screen->frame_size = params->frame_size; screen->rotation = params->rotation; if (screen->rotation) { LOGI("Initial display rotation set to %u", screen->rotation); } struct sc_size content_size = get_rotated_size(screen->frame_size, screen->rotation); screen->content_size = content_size; struct sc_size window_size = get_initial_optimal_size(content_size,params->window_width, params->window_height); uint32_t window_flags = SDL_WINDOW_HIDDEN | SDL_WINDOW_RESIZABLE | SDL_WINDOW_ALLOW_HIGHDPI; if (params->always_on_top) { window_flags |= SDL_WINDOW_ALWAYS_ON_TOP; } if (params->window_borderless) { window_flags |= SDL_WINDOW_BORDERLESS; } int x = params->window_x != SC_WINDOW_POSITION_UNDEFINED ? params->window_x : (int) SDL_WINDOWPOS_UNDEFINED; int y = params->window_y != SC_WINDOW_POSITION_UNDEFINED ? params->window_y : (int) SDL_WINDOWPOS_UNDEFINED; screen->window = SDL_CreateWindow(params->window_title, x, y, window_size.width, window_size.height, window_flags); if (!screen->window) { LOGC("Could not create window: %s", SDL_GetError()); goto error_destroy_fps_counter; } screen->renderer = SDL_CreateRenderer(screen->window, -1, SDL_RENDERER_ACCELERATED); if (!screen->renderer) { LOGC("Could not create renderer: %s", SDL_GetError()); goto error_destroy_window; } SDL_RendererInfo renderer_info; int r = SDL_GetRendererInfo(screen->renderer, &renderer_info); const char *renderer_name = r ? NULL : renderer_info.name; LOGI("Renderer: %s", renderer_name ? renderer_name : "(unknown)"); screen->mipmaps = false; // starts with "opengl" bool use_opengl = renderer_name && !strncmp(renderer_name, "opengl", 6); if (use_opengl) { struct sc_opengl *gl = &screen->gl; sc_opengl_init(gl); LOGI("OpenGL version: %s", gl->version); if (params->mipmaps) { bool supports_mipmaps = sc_opengl_version_at_least(gl, 3, 0, /* OpenGL 3.0+ */ 2, 0 /* OpenGL ES 2.0+ */); if (supports_mipmaps) { LOGI("Trilinear filtering enabled"); screen->mipmaps = true; } else { LOGW("Trilinear filtering disabled " "(OpenGL 3.0+ or ES 2.0+ required)"); } } else { LOGI("Trilinear filtering disabled"); } } else if (params->mipmaps) { LOGD("Trilinear filtering disabled (not an OpenGL renderer)"); } SDL_Surface *icon = scrcpy_icon_load(); if (icon) { SDL_SetWindowIcon(screen->window, icon); scrcpy_icon_destroy(icon); } else { LOGW("Could not load icon"); } LOGI("Initial texture: %" PRIu16 "x%" PRIu16, params->frame_size.width, params->frame_size.height); screen->texture = create_texture(screen); if (!screen->texture) { LOGC("Could not create texture: %s", SDL_GetError()); goto error_destroy_renderer; } screen->frame = av_frame_alloc(); if (!screen->frame) { LOG_OOM(); goto error_destroy_texture; } struct input_manager_params im_params = { .controller = params->controller, .screen = screen, .kp = params->kp, .mp = params->mp, .control = params->control, .forward_all_clicks = params->forward_all_clicks, .legacy_paste = params->legacy_paste, .clipboard_autosync = params->clipboard_autosync, .shortcut_mods = params->shortcut_mods, }; input_manager_init(&screen->im, &im_params); // Reset the window size to trigger a SIZE_CHANGED event, to workaround // HiDPI issues with some SDL renderers when several displays having // different HiDPI scaling are connected SDL_SetWindowSize(screen->window, window_size.width, window_size.height); sc_screen_update_content_rect(screen); if (params->fullscreen) { sc_screen_switch_fullscreen(screen); } #ifdef CONTINUOUS_RESIZING_WORKAROUND SDL_AddEventWatch(event_watcher, screen); #endif static const struct sc_frame_sink_ops ops = { .open = sc_screen_frame_sink_open, .close = sc_screen_frame_sink_close, .push = sc_screen_frame_sink_push, }; screen->frame_sink.ops = &ops; #ifndef NDEBUG screen->open = false; #endif return true; error_destroy_texture: SDL_DestroyTexture(screen->texture); error_destroy_renderer: SDL_DestroyRenderer(screen->renderer); error_destroy_window: SDL_DestroyWindow(screen->window); error_destroy_fps_counter: fps_counter_destroy(&screen->fps_counter); error_stop_and_join_video_buffer: sc_video_buffer_stop(&screen->vb); sc_video_buffer_join(&screen->vb); error_destroy_video_buffer: sc_video_buffer_destroy(&screen->vb); return false; } static void sc_screen_show_window(struct sc_screen *screen) { SDL_ShowWindow(screen->window); } void sc_screen_hide_window(struct sc_screen *screen) { SDL_HideWindow(screen->window); } void sc_screen_interrupt(struct sc_screen *screen) { sc_video_buffer_stop(&screen->vb); fps_counter_interrupt(&screen->fps_counter); } void sc_screen_join(struct sc_screen *screen) { sc_video_buffer_join(&screen->vb); fps_counter_join(&screen->fps_counter); } void sc_screen_destroy(struct sc_screen *screen) { #ifndef NDEBUG assert(!screen->open); #endif av_frame_free(&screen->frame); SDL_DestroyTexture(screen->texture); SDL_DestroyRenderer(screen->renderer); SDL_DestroyWindow(screen->window); fps_counter_destroy(&screen->fps_counter); sc_video_buffer_destroy(&screen->vb); } static void resize_for_content(struct sc_screen *screen, struct sc_size old_content_size, struct sc_size new_content_size) { struct sc_size window_size = get_window_size(screen); struct sc_size target_size = { .width = (uint32_t) window_size.width * new_content_size.width / old_content_size.width, .height = (uint32_t) window_size.height * new_content_size.height / old_content_size.height, }; target_size = get_optimal_size(target_size, new_content_size, true); set_window_size(screen, target_size); } static void set_content_size(struct sc_screen *screen, struct sc_size new_content_size) { if (!screen->fullscreen && !screen->maximized) { resize_for_content(screen, screen->content_size, new_content_size); } else if (!screen->resize_pending) { // Store the windowed size to be able to compute the optimal size once // fullscreen and maximized are disabled screen->windowed_content_size = screen->content_size; screen->resize_pending = true; } screen->content_size = new_content_size; } static void apply_pending_resize(struct sc_screen *screen) { assert(!screen->fullscreen); assert(!screen->maximized); if (screen->resize_pending) { resize_for_content(screen, screen->windowed_content_size, screen->content_size); screen->resize_pending = false; } } void sc_screen_set_rotation(struct sc_screen *screen, unsigned rotation) { assert(rotation < 4); if (rotation == screen->rotation) { return; } struct sc_size new_content_size = get_rotated_size(screen->frame_size, rotation); set_content_size(screen, new_content_size); screen->rotation = rotation; LOGI("Display rotation set to %u", rotation); sc_screen_render(screen, true); } // recreate the texture and resize the window if the frame size has changed static bool prepare_for_frame(struct sc_screen *screen, struct sc_size new_frame_size) { if (screen->frame_size.width != new_frame_size.width || screen->frame_size.height != new_frame_size.height) { // frame dimension changed, destroy texture SDL_DestroyTexture(screen->texture); screen->frame_size = new_frame_size; struct sc_size new_content_size = get_rotated_size(new_frame_size, screen->rotation); set_content_size(screen, new_content_size); sc_screen_update_content_rect(screen); LOGI("New texture: %" PRIu16 "x%" PRIu16, screen->frame_size.width, screen->frame_size.height); screen->texture = create_texture(screen); if (!screen->texture) { LOGC("Could not create texture: %s", SDL_GetError()); return false; } } return true; } // write the frame into the texture static void update_texture(struct sc_screen *screen, const AVFrame *frame) { SDL_UpdateYUVTexture(screen->texture, NULL, frame->data[0], frame->linesize[0], frame->data[1], frame->linesize[1], frame->data[2], frame->linesize[2]); if (screen->mipmaps) { SDL_GL_BindTexture(screen->texture, NULL, NULL); screen->gl.GenerateMipmap(GL_TEXTURE_2D); SDL_GL_UnbindTexture(screen->texture); } } static bool sc_screen_update_frame(struct sc_screen *screen) { av_frame_unref(screen->frame); sc_video_buffer_consume(&screen->vb, screen->frame); AVFrame *frame = screen->frame; fps_counter_add_rendered_frame(&screen->fps_counter); struct sc_size new_frame_size = {frame->width, frame->height}; if (!prepare_for_frame(screen, new_frame_size)) { return false; } update_texture(screen, frame); sc_screen_render(screen, false); return true; } void sc_screen_switch_fullscreen(struct sc_screen *screen) { uint32_t new_mode = screen->fullscreen ? 0 : SDL_WINDOW_FULLSCREEN_DESKTOP; if (SDL_SetWindowFullscreen(screen->window, new_mode)) { LOGW("Could not switch fullscreen mode: %s", SDL_GetError()); return; } screen->fullscreen = !screen->fullscreen; if (!screen->fullscreen && !screen->maximized) { apply_pending_resize(screen); } LOGD("Switched to %s mode", screen->fullscreen ? "fullscreen" : "windowed"); sc_screen_render(screen, true); } void sc_screen_resize_to_fit(struct sc_screen *screen) { if (screen->fullscreen || screen->maximized) { return; } struct sc_point point = get_window_position(screen); struct sc_size window_size = get_window_size(screen); struct sc_size optimal_size = get_optimal_size(window_size, screen->content_size, false); // Center the window related to the device screen assert(optimal_size.width <= window_size.width); assert(optimal_size.height <= window_size.height); uint32_t new_x = point.x + (window_size.width - optimal_size.width) / 2; uint32_t new_y = point.y + (window_size.height - optimal_size.height) / 2; SDL_SetWindowSize(screen->window, optimal_size.width, optimal_size.height); SDL_SetWindowPosition(screen->window, new_x, new_y); LOGD("Resized to optimal size: %ux%u", optimal_size.width, optimal_size.height); } void sc_screen_resize_to_pixel_perfect(struct sc_screen *screen) { if (screen->fullscreen) { return; } if (screen->maximized) { SDL_RestoreWindow(screen->window); screen->maximized = false; } struct sc_size content_size = screen->content_size; SDL_SetWindowSize(screen->window, content_size.width, content_size.height); LOGD("Resized to pixel-perfect: %ux%u", content_size.width, content_size.height); } static inline bool sc_screen_is_mouse_capture_key(SDL_Keycode key) { return key == SDLK_LALT || key == SDLK_LGUI || key == SDLK_RGUI; } bool sc_screen_handle_event(struct sc_screen *screen, SDL_Event *event) { switch (event->type) { case EVENT_NEW_FRAME: if (!screen->has_frame) { screen->has_frame = true; // this is the very first frame, show the window sc_screen_show_window(screen); } bool ok = sc_screen_update_frame(screen); if (!ok) { LOGW("Frame update failed\n"); } return true; case SDL_WINDOWEVENT: if (!screen->has_frame) { // Do nothing return true; } switch (event->window.event) { case SDL_WINDOWEVENT_EXPOSED: sc_screen_render(screen, true); break; case SDL_WINDOWEVENT_SIZE_CHANGED: sc_screen_render(screen, true); break; case SDL_WINDOWEVENT_MAXIMIZED: screen->maximized = true; break; case SDL_WINDOWEVENT_RESTORED: if (screen->fullscreen) { // On Windows, in maximized+fullscreen, disabling // fullscreen mode unexpectedly triggers the "restored" // then "maximized" events, leaving the window in a // weird state (maximized according to the events, but // not maximized visually). break; } screen->maximized = false; apply_pending_resize(screen); sc_screen_render(screen, true); break; case SDL_WINDOWEVENT_FOCUS_LOST: if (screen->im.mp->relative_mode) { sc_screen_capture_mouse(screen, false); } break; } return true; case SDL_KEYDOWN: if (screen->im.mp->relative_mode) { SDL_Keycode key = event->key.keysym.sym; if (sc_screen_is_mouse_capture_key(key)) { if (!screen->mouse_capture_key_pressed) { screen->mouse_capture_key_pressed = key; return true; } else { // Another mouse capture key has been pressed, cancel // mouse (un)capture screen->mouse_capture_key_pressed = 0; // Do not return, the event must be forwarded to the // input manager } } } break; case SDL_KEYUP: if (screen->im.mp->relative_mode) { SDL_Keycode key = event->key.keysym.sym; SDL_Keycode cap = screen->mouse_capture_key_pressed; screen->mouse_capture_key_pressed = 0; if (key == cap) { // A mouse capture key has been pressed then released: // toggle the capture mouse mode sc_screen_capture_mouse(screen, !screen->mouse_captured); return true; } // Do not return, the event must be forwarded to the input // manager } break; case SDL_MOUSEWHEEL: case SDL_MOUSEMOTION: case SDL_MOUSEBUTTONDOWN: if (screen->im.mp->relative_mode && !screen->mouse_captured) { // Do not forward to input manager, the mouse will be captured // on SDL_MOUSEBUTTONUP return true; } break; case SDL_FINGERMOTION: case SDL_FINGERDOWN: case SDL_FINGERUP: if (screen->im.mp->relative_mode) { // Touch events are not compatible with relative mode // (coordinates are not relative) return true; } break; case SDL_MOUSEBUTTONUP: if (screen->im.mp->relative_mode && !screen->mouse_captured) { sc_screen_capture_mouse(screen, true); return true; } } return input_manager_handle_event(&screen->im, event); } struct sc_point sc_screen_convert_drawable_to_frame_coords(struct sc_screen *screen, int32_t x, int32_t y) { unsigned rotation = screen->rotation; assert(rotation < 4); int32_t w = screen->content_size.width; int32_t h = screen->content_size.height; x = (int64_t) (x - screen->rect.x) * w / screen->rect.w; y = (int64_t) (y - screen->rect.y) * h / screen->rect.h; // rotate struct sc_point result; switch (rotation) { case 0: result.x = x; result.y = y; break; case 1: result.x = h - y; result.y = x; break; case 2: result.x = w - x; result.y = h - y; break; default: assert(rotation == 3); result.x = y; result.y = w - x; break; } return result; } struct sc_point sc_screen_convert_window_to_frame_coords(struct sc_screen *screen, int32_t x, int32_t y) { sc_screen_hidpi_scale_coords(screen, &x, &y); return sc_screen_convert_drawable_to_frame_coords(screen, x, y); } void sc_screen_hidpi_scale_coords(struct sc_screen *screen, int32_t *x, int32_t *y) { // take the HiDPI scaling (dw/ww and dh/wh) into account int ww, wh, dw, dh; SDL_GetWindowSize(screen->window, &ww, &wh); SDL_GL_GetDrawableSize(screen->window, &dw, &dh); // scale for HiDPI (64 bits for intermediate multiplications) *x = (int64_t) *x * dw / ww; *y = (int64_t) *y * dh / wh; }