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Merged
merged 2 commits into from
Mar 17, 2021
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(nut-tree/nut.js/183) Determine scale factor ifor high DPI displays i… #59

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(nut-tree/nut.js/183) Determine scale factor ifor high DPI displays i…
s1hofmann Mar 4, 2021
7af9574
(#183) Merge develop
s1hofmann Mar 17, 2021
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44 changes: 31 additions & 13 deletions src/win32/screengrab.c
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Original file line number Diff line number Diff line change
Expand Up @@ -2,6 +2,22 @@
#include "../endian.h"
#include <stdlib.h> /* malloc() */

MMRect getScaledRect(MMRect input, HDC imageSource) {
BITMAP structBitmapHeader;
memset( &structBitmapHeader, 0, sizeof(BITMAP) );

HGDIOBJ hBitmap = GetCurrentObject(imageSource, OBJ_BITMAP);
GetObject(hBitmap, sizeof(BITMAP), &structBitmapHeader);

size_t desktopWidth = (size_t)GetSystemMetrics(SM_CXSCREEN);
size_t desktopHeight = (size_t)GetSystemMetrics(SM_CYSCREEN);

double scaleX = (double)(structBitmapHeader.bmWidth / desktopWidth);
double scaleY = (double)(structBitmapHeader.bmHeight / desktopHeight);

return MMRectMake(input.origin.x, input.origin.y, input.size.width * scaleX, input.size.height * scaleY);
}

MMBitmapRef copyMMBitmapFromDisplayInRect(MMRect rect)
{
MMBitmapRef bitmap;
Expand All @@ -10,22 +26,24 @@ MMBitmapRef copyMMBitmapFromDisplayInRect(MMRect rect)
HBITMAP dib;
BITMAPINFO bi;

screen = GetWindowDC(NULL); /* Get entire screen */
MMRect scaledRect = getScaledRect(rect, screen);

if (screen == NULL) return NULL;

/* Initialize bitmap info. */
bi.bmiHeader.biSize = sizeof(bi.bmiHeader);
bi.bmiHeader.biWidth = (long)rect.size.width;
bi.bmiHeader.biHeight = -(long)rect.size.height; /* Non-cartesian, please */
bi.bmiHeader.biWidth = (long)scaledRect.size.width;
bi.bmiHeader.biHeight = -(long)scaledRect.size.height; /* Non-cartesian, please */
bi.bmiHeader.biPlanes = 1;
bi.bmiHeader.biBitCount = 32;
bi.bmiHeader.biCompression = BI_RGB;
bi.bmiHeader.biSizeImage = (DWORD)(4 * rect.size.width * rect.size.height);
bi.bmiHeader.biSizeImage = (DWORD)(4 * scaledRect.size.width * scaledRect.size.height);
bi.bmiHeader.biXPelsPerMeter = 0;
bi.bmiHeader.biYPelsPerMeter = 0;
bi.bmiHeader.biClrUsed = 0;
bi.bmiHeader.biClrImportant = 0;

screen = GetDC(NULL); /* Get entire screen */
if (screen == NULL) return NULL;

/* Get screen data in display device context. */
dib = CreateDIBSection(screen, &bi, DIB_RGB_COLORS, &data, NULL, 0);

Expand All @@ -35,11 +53,11 @@ MMBitmapRef copyMMBitmapFromDisplayInRect(MMRect rect)
!BitBlt(screenMem,
(int)0,
(int)0,
(int)rect.size.width,
(int)rect.size.height,
(int)scaledRect.size.width,
(int)scaledRect.size.height,
screen,
rect.origin.x,
rect.origin.y,
scaledRect.origin.x,
scaledRect.origin.y,
SRCCOPY)) {

/* Error copying data. */
Expand All @@ -51,9 +69,9 @@ MMBitmapRef copyMMBitmapFromDisplayInRect(MMRect rect)
}

bitmap = createMMBitmap(NULL,
rect.size.width,
rect.size.height,
4 * rect.size.width,
scaledRect.size.width,
scaledRect.size.height,
4 * scaledRect.size.width,
(uint8_t)bi.bmiHeader.biBitCount,
4);

Expand Down