Fix GIF and Overlay issues; Release NightShot v0.19

include/capture.hpp

@@ -2,26 +2,57 @@
 #include "config.hpp"
 #include <windows.h>
 
-struct ScreenCapture {
+#include <cstdint>
+#include <vector>
+
+struct ScreenCaptureSurface {
     HDC memoryDc = nullptr;
     HBITMAP bitmap = nullptr;
     HGDIOBJ oldBitmap = nullptr;
-    void* pixels = nullptr;
-    int x = 0;
-    int y = 0;
+    std::uint8_t* pixels = nullptr;
+    RECT rect{}; // local coordinates inside the virtual-desktop window
     int width = 0;
     int height = 0;
     int stride = 0;
 
-    ScreenCapture() = default;
-    ScreenCapture(const ScreenCapture&) = delete;
-    ScreenCapture& operator=(const ScreenCapture&) = delete;
-    ScreenCapture(ScreenCapture&& other) noexcept;
-    ScreenCapture& operator=(ScreenCapture&& other) noexcept;
-    ~ScreenCapture();
+    ScreenCaptureSurface() = default;
+    ScreenCaptureSurface(const ScreenCaptureSurface&) = delete;
+    ScreenCaptureSurface& operator=(const ScreenCaptureSurface&) = delete;
+    ScreenCaptureSurface(ScreenCaptureSurface&& other) noexcept;
+    ScreenCaptureSurface& operator=(ScreenCaptureSurface&& other) noexcept;
+    ~ScreenCaptureSurface();
 
-    [[nodiscard]] bool valid() const noexcept { return memoryDc && bitmap && width > 0 && height > 0; }
+    [[nodiscard]] bool valid() const noexcept {
+        return memoryDc && bitmap && pixels && width > 0 && height > 0;
+    }
     void reset() noexcept;
 };
 
+struct ScreenCapture {
+    int x = 0;
+    int y = 0;
+    int width = 0;
+    int height = 0;
+    std::vector<ScreenCaptureSurface> surfaces;
+
+    ScreenCapture() = default;
+    ScreenCapture(const ScreenCapture&) = delete;
+    ScreenCapture& operator=(const ScreenCapture&) = delete;
+    ScreenCapture(ScreenCapture&&) noexcept = default;
+    ScreenCapture& operator=(ScreenCapture&&) noexcept = default;
+    ~ScreenCapture() = default;
+
+    [[nodiscard]] bool valid() const noexcept {
+        return width > 0 && height > 0 && !surfaces.empty();
+    }
+
+    // Copies a local virtual-desktop rectangle into destination. Empty space
+    // between physically arranged monitors is filled with black instead of
+    // forcing NightShot to keep one enormous bounding-box DIB in RAM.
+    [[nodiscard]] bool blitTo(HDC destination, int destinationX, int destinationY,
+                              const RECT& sourceLocal) const noexcept;
+
+    [[nodiscard]] bool samplePixel(int localX, int localY, COLORREF& color) const noexcept;
+};
+
 [[nodiscard]] ScreenCapture captureVirtualDesktop();