1 files changed, 126 insertions, 0 deletions
diff --git a/windows/utils/screenshot.c b/windows/utils/screenshot.c
new file mode 100644
index 00000000..777520fd
--- /dev/null
+++ b/windows/utils/screenshot.c
@@ -0,0 +1,126 @@
+#include "putty.h"
+
+#if HAVE_DWMAPI_H
+
+#include <dwmapi.h>
+
+char *save_screenshot(HWND hwnd, const char *outfile)
+{
+    HDC dcWindow = NULL, dcSave = NULL;
+    HBITMAP bmSave = NULL;
+    uint8_t *buffer = NULL;
+    char *err = NULL;
+
+    static HMODULE dwmapi_module;
+    DECL_WINDOWS_FUNCTION(static, HRESULT, DwmGetWindowAttribute,
+                          (HWND, DWORD, PVOID, DWORD));
+
+    if (!dwmapi_module) {
+        dwmapi_module = load_system32_dll("dwmapi.dll");
+        GET_WINDOWS_FUNCTION(dwmapi_module, DwmGetWindowAttribute);
+    }
+
+    dcWindow = GetDC(NULL);
+    if (!dcWindow) {
+        err = dupprintf("GetDC(window): %s", win_strerror(GetLastError()));
+        goto out;
+    }
+
+    int x, y, w, h;
+    RECT wr;
+
+    /* Use DwmGetWindowAttribute in place of GetWindowRect to exclude
+     * drop shadow, otherwise we get a load of unwanted desktop
+     * background under the shadow */
+    if (p_DwmGetWindowAttribute &&
+        0 <= p_DwmGetWindowAttribute(hwnd, DWMWA_EXTENDED_FRAME_BOUNDS,
+                                     &wr, sizeof(wr))) {
+        x = wr.left;
+        y = wr.top;
+        w = wr.right - wr.left;
+        h = wr.bottom - wr.top;
+    } else {
+        BITMAP bmhdr;
+        memset(&bmhdr, 0, sizeof(bmhdr));
+        GetObject(GetCurrentObject(dcWindow, OBJ_BITMAP),
+                  sizeof(bmhdr), &bmhdr);
+        x = y = 0;
+        w = bmhdr.bmWidth;
+        h = bmhdr.bmHeight;
+    }
+
+    dcSave = CreateCompatibleDC(dcWindow);
+    if (!dcSave) {
+        err = dupprintf("CreateCompatibleDC(desktop window dc): %s",
+                        win_strerror(GetLastError()));
+        goto out;
+    }
+
+    bmSave = CreateCompatibleBitmap(dcWindow, w, h);
+    if (!bmSave) {
+        err = dupprintf("CreateCompatibleBitmap: %s",
+                        win_strerror(GetLastError()));
+        goto out;
+    }
+
+    if (!SelectObject(dcSave, bmSave)) {
+        err = dupprintf("SelectObject: %s", win_strerror(GetLastError()));
+        goto out;
+    }
+
+    if (!BitBlt(dcSave, 0, 0, w, h, dcWindow, x, y, SRCCOPY)) {
+        err = dupprintf("BitBlt: %s", win_strerror(GetLastError()));
+        goto out;
+    }
+
+    BITMAPINFO bmInfo;
+    memset(&bmInfo, 0, sizeof(bmInfo));
+    bmInfo.bmiHeader.biSize = sizeof(bmInfo.bmiHeader);
+    bmInfo.bmiHeader.biWidth = w;
+    bmInfo.bmiHeader.biHeight = h;
+    bmInfo.bmiHeader.biPlanes = 1;
+    bmInfo.bmiHeader.biBitCount = 32;
+    bmInfo.bmiHeader.biCompression = BI_RGB;
+
+    size_t bmPixels = (size_t)w*h, bmBytes = bmPixels * 4;
+    buffer = snewn(bmBytes, uint8_t);
+
+    if (!GetDIBits(dcWindow, bmSave, 0, h, buffer, &bmInfo, DIB_RGB_COLORS))
+        err = dupprintf("GetDIBits (get data): %s",
+                        win_strerror(GetLastError()));
+
+    FILE *fp = fopen(outfile, "wb");
+    if (!fp) {
+        err = dupprintf("'%s': unable to open file", outfile);
+        goto out;
+    }
+
+    BITMAPFILEHEADER bmFileHdr;
+    bmFileHdr.bfType = 'B' | ('M' << 8);
+    bmFileHdr.bfSize = sizeof(bmFileHdr) + sizeof(bmInfo.bmiHeader) + bmBytes;
+    bmFileHdr.bfOffBits = sizeof(bmFileHdr) + sizeof(bmInfo.bmiHeader);
+    fwrite((void *)&bmFileHdr, 1, sizeof(bmFileHdr), fp);
+    fwrite((void *)&bmInfo.bmiHeader, 1, sizeof(bmInfo.bmiHeader), fp);
+    fwrite((void *)buffer, 1, bmBytes, fp);
+    fclose(fp);
+
+  out:
+    if (dcWindow)
+        ReleaseDC(NULL, dcWindow);
+    if (bmSave)
+        DeleteObject(bmSave);
+    if (dcSave)
+        DeleteObject(dcSave);
+    sfree(buffer);
+    return err;
+}
+
+#else /* HAVE_DWMAPI_H */
+
+/* Without <dwmapi.h> we can't get the right window rectangle */
+char *save_screenshot(HWND hwnd, const char *outfile)
+{
+    return dupstr("Demo screenshots not compiled in to this build");
+}
+
+#endif /* HAVE_DWMAPI_H */