fix: touch scaling bug and initialize display variables as 0 (#4758)

Co-authored-by: Chase Payne <27069224+nonary@users.noreply.github.com>

Author: ReenigneArcher

src/platform/common.h

@@ -485,10 +485,7 @@ namespace platf {
      */
     using pull_free_image_cb_t = std::function<bool(std::shared_ptr<img_t> &img_out)>;
 
-    display_t() noexcept:
-        offset_x {0},
-        offset_y {0} {
-    }
+    display_t() noexcept = default;
 
     /**
      * @brief Capture a frame.
@@ -538,16 +535,16 @@ namespace platf {
     virtual ~display_t() = default;
 
     // Offsets for when streaming a specific monitor. By default, they are 0.
-    int offset_x;
-    int offset_y;
-    int env_width;
-    int env_height;
-    int env_logical_width;
-    int env_logical_height;
-    int width;
-    int height;
-    int logical_width;
-    int logical_height;
+    int offset_x {0};
+    int offset_y {0};
+    int env_width {0};
+    int env_height {0};
+    int env_logical_width {0};
+    int env_logical_height {0};
+    int width {0};
+    int height {0};
+    int logical_width {0};
+    int logical_height {0};
 
   protected:
     // collect capture timing data (at loglevel debug)

src/platform/windows/input.cpp

@@ -513,8 +513,10 @@ namespace platf {
       // MOUSEEVENTF_VIRTUALDESK maps to the entirety of the desktop rather than the primary desktop
       MOUSEEVENTF_VIRTUALDESK;
 
-    auto scaled_x = std::lround((x + touch_port.offset_x) * ((float) target_touch_port.width / (float) touch_port.width));
-    auto scaled_y = std::lround((y + touch_port.offset_y) * ((float) target_touch_port.height / (float) touch_port.height));
+    // Note: x and y already include the display offset (offset_x/offset_y) from client_to_touchport(),
+    // so we must not add offset_x/offset_y again here to avoid double-offsetting on multi-monitor setups.
+    auto scaled_x = std::lround(x * ((float) target_touch_port.width / (float) touch_port.width));
+    auto scaled_y = std::lround(y * ((float) target_touch_port.height / (float) touch_port.height));
 
     mi.dx = scaled_x;
     mi.dy = scaled_y;

src/video.cpp

@@ -2139,7 +2139,7 @@ namespace video {
     float scalar_tpcoords = 1.0f;
     int display_env_logical_width = 0;
     int display_env_logical_height = 0;
-    if (display->logical_width && display->logical_height && display->env_logical_width && display->env_logical_height) {
+    if (display->logical_width > 0 && display->logical_height > 0 && display->env_logical_width > 0 && display->env_logical_height > 0) {
       float lwd = display->logical_width;
       float lhd = display->logical_height;
       scalar_tpcoords = std::fminf(wd / lwd, hd / lhd);