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added right mouse button drag to move image on surface

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Ano-sys
2026-08-15 18:01:33 +02:00
parent a395470d88
commit 3487bdfb1f
1 changed files with 31 additions and 12 deletions
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SimpleImageViewer.c
+28 -9
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@@ -95,7 +95,7 @@ SDL_Surface* create_image_surface(SDL_Surface* surface, Image* image){
return image_surface; return image_surface;
} }
void draw_image(SDL_Window* window, SDL_Surface* image_surface, Image* image, float pixel_size_delta){ void draw_image(SDL_Window* window, SDL_Surface* image_surface, Image* image, float pixel_size_delta, int image_start_x, int image_start_y){
SDL_Surface* surface = SDL_GetWindowSurface(window); SDL_Surface* surface = SDL_GetWindowSurface(window);
float pixel_size = pixel_size_delta; float pixel_size = pixel_size_delta;
@@ -105,7 +105,7 @@ void draw_image(SDL_Window* window, SDL_Surface* image_surface, Image* image, fl
Uint64 start = SDL_GetTicksNS(); Uint64 start = SDL_GetTicksNS();
SDL_Rect dst = { center_x - (image->x * pixel_size / 2), center_y - (image->y * pixel_size / 2), image->x * pixel_size, image->y * pixel_size }; SDL_Rect dst = { center_x - (image->x * pixel_size / 2) + image_start_x, center_y - (image->y * pixel_size / 2) + image_start_y, image->x * pixel_size, image->y * pixel_size };
SDL_ClearSurface(surface, 0, 0, 0, 255); SDL_ClearSurface(surface, 0, 0, 0, 255);
SDL_BlitSurfaceScaled(image_surface, NULL, surface, &dst, SDL_SCALEMODE_LINEAR); SDL_BlitSurfaceScaled(image_surface, NULL, surface, &dst, SDL_SCALEMODE_LINEAR);
@@ -153,7 +153,8 @@ void on_wheel(SDL_Event* event, SDL_Window* window){
} }
void loop(SDL_Window* window, SDL_Surface* image_surface, Image* image){ void loop(SDL_Window* window, SDL_Surface* image_surface, Image* image){
bool drag_mouse = false; bool drag_left_mouse = false;
bool drag_right_mouse = false;
int last_pointer_x = 0; int last_pointer_x = 0;
int last_pointer_y = 0; int last_pointer_y = 0;
@@ -161,6 +162,8 @@ void loop(SDL_Window* window, SDL_Surface* image_surface, Image* image){
bool run = true; bool run = true;
float pixel_size_delta = 1.0f; float pixel_size_delta = 1.0f;
int current_image_start_x = 0, current_image_start_y = 0;
int image_start_at_drag_x = 0, image_start_at_drag_y = 0;
bool redraw = false; bool redraw = false;
@@ -176,17 +179,33 @@ void loop(SDL_Window* window, SDL_Surface* image_surface, Image* image){
} }
} }
if(event.type == SDL_EVENT_QUIT || event.type == SDL_EVENT_WINDOW_CLOSE_REQUESTED) run = false; if(event.type == SDL_EVENT_QUIT || event.type == SDL_EVENT_WINDOW_CLOSE_REQUESTED) run = false;
if(event.type == SDL_EVENT_MOUSE_BUTTON_DOWN && event.button.button == SDL_BUTTON_LEFT){ if(event.type == SDL_EVENT_MOUSE_BUTTON_DOWN){
drag_mouse = true; if(event.button.button == SDL_BUTTON_LEFT) drag_left_mouse = true;
if(event.button.button == SDL_BUTTON_RIGHT) drag_right_mouse = true;
last_pointer_x = (int)event.button.x; last_pointer_x = (int)event.button.x;
last_pointer_y = (int)event.button.y; last_pointer_y = (int)event.button.y;
image_start_at_drag_x = current_image_start_x;
image_start_at_drag_y = current_image_start_y;
} }
if(event.type == SDL_EVENT_MOUSE_BUTTON_UP && event.button.button == SDL_BUTTON_LEFT) drag_mouse = false; if(event.type == SDL_EVENT_MOUSE_BUTTON_UP && event.button.button == SDL_BUTTON_LEFT) drag_left_mouse = false;
if(event.type == SDL_EVENT_MOUSE_MOTION && drag_mouse){ if(event.type == SDL_EVENT_MOUSE_BUTTON_UP && event.button.button == SDL_BUTTON_RIGHT) drag_right_mouse = false;
if(event.type == SDL_EVENT_MOUSE_MOTION){
if(drag_left_mouse){
int last_x, last_y; int last_x, last_y;
SDL_GetWindowPosition(window, &last_x, &last_y); SDL_GetWindowPosition(window, &last_x, &last_y);
SDL_SetWindowPosition(window, last_x + (int)event.motion.x - last_pointer_x, last_y + (int)event.motion.y - last_pointer_y); SDL_SetWindowPosition(window, last_x + (int)event.motion.x - last_pointer_x, last_y + (int)event.motion.y - last_pointer_y);
} }
if(drag_right_mouse){
int image_start_x = (int)event.motion.x - last_pointer_x + image_start_at_drag_x;
int image_start_y = (int)event.motion.y - last_pointer_y + image_start_at_drag_y;
current_image_start_x = image_start_x;
current_image_start_y = image_start_y;
redraw = true;
}
}
if(event.type == SDL_EVENT_MOUSE_WHEEL){ if(event.type == SDL_EVENT_MOUSE_WHEEL){
float last_pixel_size_delta = pixel_size_delta; float last_pixel_size_delta = pixel_size_delta;
pixel_size_delta += event.wheel.y * 0.1f * pixel_size_delta; pixel_size_delta += event.wheel.y * 0.1f * pixel_size_delta;
@@ -202,7 +221,7 @@ void loop(SDL_Window* window, SDL_Surface* image_surface, Image* image){
if(redraw){ if(redraw){
redraw = false; redraw = false;
draw_image(window, image_surface, image, pixel_size_delta); draw_image(window, image_surface, image, pixel_size_delta, current_image_start_x, current_image_start_y);
} }
} }
} }
@@ -241,7 +260,7 @@ int main(int argc, char** argv){
SDL_Surface* image_surface = create_image_surface(surface, &image); SDL_Surface* image_surface = create_image_surface(surface, &image);
free_image_buffer(&image); free_image_buffer(&image);
draw_image(window, image_surface, &image, 1.0f); draw_image(window, image_surface, &image, 1.0f, 0, 0);
SDL_UpdateWindowSurface(window); SDL_UpdateWindowSurface(window);