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/*
* Copyright (c) 2013 The WebRTC project authors. All Rights Reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
#include "modules/desktop_capture/win/cursor.h"
#include <algorithm>
#include <memory>
#include "modules/desktop_capture/desktop_frame.h"
#include "modules/desktop_capture/desktop_geometry.h"
#include "modules/desktop_capture/mouse_cursor.h"
#include "modules/desktop_capture/win/scoped_gdi_object.h"
#include "rtc_base/logging.h"
#include "rtc_base/system/arch.h"
namespace webrtc {
namespace {
#if defined(WEBRTC_ARCH_LITTLE_ENDIAN)
#define RGBA(r, g, b, a) \
((((a) << 24) & 0xff000000) | (((b) << 16) & 0xff0000) | \
(((g) << 8) & 0xff00) | ((r)&0xff))
#else // !defined(WEBRTC_ARCH_LITTLE_ENDIAN)
#define RGBA(r, g, b, a) \
((((r) << 24) & 0xff000000) | (((g) << 16) & 0xff0000) | \
(((b) << 8) & 0xff00) | ((a)&0xff))
#endif // !defined(WEBRTC_ARCH_LITTLE_ENDIAN)
const int kBytesPerPixel = DesktopFrame::kBytesPerPixel;
// Pixel colors used when generating cursor outlines.
const uint32_t kPixelRgbaBlack = RGBA(0, 0, 0, 0xff);
const uint32_t kPixelRgbaWhite = RGBA(0xff, 0xff, 0xff, 0xff);
const uint32_t kPixelRgbaTransparent = RGBA(0, 0, 0, 0);
const uint32_t kPixelRgbWhite = RGB(0xff, 0xff, 0xff);
// Expands the cursor shape to add a white outline for visibility against
// dark backgrounds.
void AddCursorOutline(int width, int height, uint32_t* data) {
for (int y = 0; y < height; y++) {
for (int x = 0; x < width; x++) {
// If this is a transparent pixel (bgr == 0 and alpha = 0), check the
// neighbor pixels to see if this should be changed to an outline pixel.
if (*data == kPixelRgbaTransparent) {
// Change to white pixel if any neighbors (top, bottom, left, right)
// are black.
if ((y > 0 && data[-width] == kPixelRgbaBlack) ||
(y < height - 1 && data[width] == kPixelRgbaBlack) ||
(x > 0 && data[-1] == kPixelRgbaBlack) ||
(x < width - 1 && data[1] == kPixelRgbaBlack)) {
*data = kPixelRgbaWhite;
}
}
data++;
}
}
}
// Premultiplies RGB components of the pixel data in the given image by
// the corresponding alpha components.
void AlphaMul(uint32_t* data, int width, int height) {
static_assert(sizeof(uint32_t) == kBytesPerPixel,
"size of uint32 should be the number of bytes per pixel");
for (uint32_t* data_end = data + width * height; data != data_end; ++data) {
RGBQUAD* from = reinterpret_cast<RGBQUAD*>(data);
RGBQUAD* to = reinterpret_cast<RGBQUAD*>(data);
to->rgbBlue =
(static_cast<uint16_t>(from->rgbBlue) * from->rgbReserved) / 0xff;
to->rgbGreen =
(static_cast<uint16_t>(from->rgbGreen) * from->rgbReserved) / 0xff;
to->rgbRed =
(static_cast<uint16_t>(from->rgbRed) * from->rgbReserved) / 0xff;
}
}
// Scans a 32bpp bitmap looking for any pixels with non-zero alpha component.
// Returns true if non-zero alpha is found. `stride` is expressed in pixels.
bool HasAlphaChannel(const uint32_t* data, int stride, int width, int height) {
const RGBQUAD* plane = reinterpret_cast<const RGBQUAD*>(data);
for (int y = 0; y < height; ++y) {
for (int x = 0; x < width; ++x) {
if (plane->rgbReserved != 0)
return true;
plane += 1;
}
plane += stride - width;
}
return false;
}
} // namespace
MouseCursor* CreateMouseCursorFromHCursor(HDC dc, HCURSOR cursor) {
ICONINFO iinfo;
if (!GetIconInfo(cursor, &iinfo)) {
RTC_LOG_F(LS_ERROR) << "Unable to get cursor icon info. Error = "
<< GetLastError();
return NULL;
}
int hotspot_x = iinfo.xHotspot;
int hotspot_y = iinfo.yHotspot;
// Make sure the bitmaps will be freed.
win::ScopedBitmap scoped_mask(iinfo.hbmMask);
win::ScopedBitmap scoped_color(iinfo.hbmColor);
bool is_color = iinfo.hbmColor != NULL;
// Get `scoped_mask` dimensions.
BITMAP bitmap_info;
if (!GetObject(scoped_mask, sizeof(bitmap_info), &bitmap_info)) {
RTC_LOG_F(LS_ERROR) << "Unable to get bitmap info. Error = "
<< GetLastError();
return NULL;
}
int width = bitmap_info.bmWidth;
int height = bitmap_info.bmHeight;
std::unique_ptr<uint32_t[]> mask_data(new uint32_t[width * height]);
// Get pixel data from `scoped_mask` converting it to 32bpp along the way.
// GetDIBits() sets the alpha component of every pixel to 0.
BITMAPV5HEADER bmi = {0};
bmi.bV5Size = sizeof(bmi);
bmi.bV5Width = width;
bmi.bV5Height = -height; // request a top-down bitmap.
bmi.bV5Planes = 1;
bmi.bV5BitCount = kBytesPerPixel * 8;
bmi.bV5Compression = BI_RGB;
bmi.bV5AlphaMask = 0xff000000;
bmi.bV5CSType = LCS_WINDOWS_COLOR_SPACE;
bmi.bV5Intent = LCS_GM_BUSINESS;
if (!GetDIBits(dc, scoped_mask, 0, height, mask_data.get(),
reinterpret_cast<BITMAPINFO*>(&bmi), DIB_RGB_COLORS)) {
RTC_LOG_F(LS_ERROR) << "Unable to get bitmap bits. Error = "
<< GetLastError();
return NULL;
}
uint32_t* mask_plane = mask_data.get();
std::unique_ptr<DesktopFrame> image(
new BasicDesktopFrame(DesktopSize(width, height)));
bool has_alpha = false;
if (is_color) {
image.reset(new BasicDesktopFrame(DesktopSize(width, height)));
// Get the pixels from the color bitmap.
if (!GetDIBits(dc, scoped_color, 0, height, image->data(),
reinterpret_cast<BITMAPINFO*>(&bmi), DIB_RGB_COLORS)) {
RTC_LOG_F(LS_ERROR) << "Unable to get bitmap bits. Error = "
<< GetLastError();
return NULL;
}
// GetDIBits() does not provide any indication whether the bitmap has alpha
// channel, so we use HasAlphaChannel() below to find it out.
has_alpha = HasAlphaChannel(reinterpret_cast<uint32_t*>(image->data()),
width, width, height);
} else {
// For non-color cursors, the mask contains both an AND and an XOR mask and
// the height includes both. Thus, the width is correct, but we need to
// divide by 2 to get the correct mask height.
height /= 2;
image.reset(new BasicDesktopFrame(DesktopSize(width, height)));
// The XOR mask becomes the color bitmap.
memcpy(image->data(), mask_plane + (width * height),
image->stride() * height);
}
// Reconstruct transparency from the mask if the color image does not has
// alpha channel.
if (!has_alpha) {
bool add_outline = false;
uint32_t* dst = reinterpret_cast<uint32_t*>(image->data());
uint32_t* mask = mask_plane;
for (int y = 0; y < height; y++) {
for (int x = 0; x < width; x++) {
// The two bitmaps combine as follows:
// mask color Windows Result Our result RGB Alpha
// 0 00 Black Black 00 ff
// 0 ff White White ff ff
// 1 00 Screen Transparent 00 00
// 1 ff Reverse-screen Black 00 ff
//
// Since we don't support XOR cursors, we replace the "Reverse Screen"
// with black. In this case, we also add an outline around the cursor
// so that it is visible against a dark background.
if (*mask == kPixelRgbWhite) {
if (*dst != 0) {
add_outline = true;
*dst = kPixelRgbaBlack;
} else {
*dst = kPixelRgbaTransparent;
}
} else {
*dst = kPixelRgbaBlack ^ *dst;
}
++dst;
++mask;
}
}
if (add_outline) {
AddCursorOutline(width, height,
reinterpret_cast<uint32_t*>(image->data()));
}
}
// Pre-multiply the resulting pixels since MouseCursor uses premultiplied
// images.
AlphaMul(reinterpret_cast<uint32_t*>(image->data()), width, height);
return new MouseCursor(image.release(), DesktopVector(hotspot_x, hotspot_y));
}
} // namespace webrtc