[英]X11 - Draw on Overlay Window
我想在屏幕上的特定像素处绘制简单的图元(类似于此问题 )。 为此,我使用“窗口管理器”的“重叠窗口”在所有窗口之上绘制。 我可以看到正在绘制的形状和鼠标事件通过,但是例如,看不到覆盖窗口下方的窗口移动(除非我杀死了我的应用程序)。 我是Xlib编程的新手,很高兴提出一个简单的问题。
#include <assert.h>
#include <stdio.h>
#include <X11/Xlib.h>
#include <X11/extensions/Xcomposite.h>
#include <X11/extensions/Xfixes.h>
#include <X11/extensions/shape.h>
#include <cairo.h>
#include <cairo-xlib.h>
Display *d;
Window overlay;
Window root;
int width, height;
void
allow_input_passthrough (Window w)
{
XserverRegion region = XFixesCreateRegion (d, NULL, 0);
XFixesSetWindowShapeRegion (d, w, ShapeBounding, 0, 0, 0);
XFixesSetWindowShapeRegion (d, w, ShapeInput, 0, 0, region);
XFixesDestroyRegion (d, region);
}
void
prep_overlay (void)
{
overlay = XCompositeGetOverlayWindow (d, root);
allow_input_passthrough (overlay);
}
void draw(cairo_t *cr) {
int quarter_w = width / 4;
int quarter_h = height / 4;
cairo_set_source_rgb(cr, 1.0, 0.0, 0.0);
cairo_rectangle(cr, quarter_w, quarter_h, quarter_w * 2, quarter_h * 2);
cairo_fill(cr);
}
int main() {
d = XOpenDisplay(NULL);
int s = DefaultScreen(d);
root = RootWindow(d, s);
XCompositeRedirectSubwindows (d, root, CompositeRedirectAutomatic);
XSelectInput (d, root, SubstructureNotifyMask);
width = DisplayWidth(d, s);
height = DisplayHeight(d, s);
prep_overlay();
cairo_surface_t *surf = cairo_xlib_surface_create(d, overlay,
DefaultVisual(d, s),
width, height);
cairo_t *cr = cairo_create(surf);
XSelectInput(d, overlay, ExposureMask);
draw(cr);
XEvent ev;
while (1) {
XNextEvent(d, &ev);
if (ev.type == Expose) {
draw(cr);
}
}
cairo_destroy(cr);
cairo_surface_destroy(surf);
XCloseDisplay(d);
return 0;
}
如何在“叠加窗口”上绘制像素并仍然看到下面的窗口?
sleep(50)
! 太多了,只有50秒。 我使用了5ms的延迟,效果很好。
您的问题似乎与运行时环境有关。 您应该已经有一个复合显示管理器正在运行。 (并非所有展示管理器都能按预期工作,因此最好尝试其他展示管理器)
我确认下面的屏幕已更新,没有任何问题,我可以与它进行互动。
运行在:
Ubuntu 15.10
Kernel 4.2.0-18-generic
X.Org X Server 1.17.2
Compiz 0.9.12.2
这里是带有延迟修改的完整代码:
#include <assert.h>
#include <stdio.h>
#include <time.h>
#include <X11/Xlib.h>
#include <X11/extensions/Xcomposite.h>
#include <X11/extensions/Xfixes.h>
#include <X11/extensions/shape.h>
#include <cairo.h>
#include <cairo-xlib.h>
Display *d;
Window overlay;
Window root;
int width, height;
void
allow_input_passthrough (Window w)
{
XserverRegion region = XFixesCreateRegion (d, NULL, 0);
XFixesSetWindowShapeRegion (d, w, ShapeBounding, 0, 0, 0);
XFixesSetWindowShapeRegion (d, w, ShapeInput, 0, 0, region);
XFixesDestroyRegion (d, region);
}
void
prep_overlay (void)
{
overlay = XCompositeGetOverlayWindow (d, root);
allow_input_passthrough (overlay);
}
void draw(cairo_t *cr) {
int quarter_w = width / 4;
int quarter_h = height / 4;
cairo_set_source_rgb(cr, 1.0, 0.0, 0.0);
cairo_rectangle(cr, quarter_w, quarter_h, quarter_w * 2, quarter_h * 2);
cairo_fill(cr);
}
int main() {
struct timespec ts = {0, 5000000};
d = XOpenDisplay(NULL);
int s = DefaultScreen(d);
root = RootWindow(d, s);
XCompositeRedirectSubwindows (d, root, CompositeRedirectAutomatic);
XSelectInput (d, root, SubstructureNotifyMask);
width = DisplayWidth(d, s);
height = DisplayHeight(d, s);
prep_overlay();
cairo_surface_t *surf = cairo_xlib_surface_create(d, overlay,
DefaultVisual(d, s),
width, height);
cairo_t *cr = cairo_create(surf);
XSelectInput(d, overlay, ExposureMask);
draw(cr);
XEvent ev;
while(1) {
overlay = XCompositeGetOverlayWindow (d, root);
draw(cr);
XCompositeReleaseOverlayWindow (d, root);
nanosleep(&ts, NULL);
}
cairo_destroy(cr);
cairo_surface_destroy(surf);
XCloseDisplay(d);
return 0;
}
请允许我提出一个更简单,纯正的X11解决方案,该解决方案不存在我所遇到的闪烁问题,并且在这里也提到过 。 它使用Xlib中的override_redirect功能:
#include <assert.h>
#include <stdio.h>
#include <X11/Xlib.h>
#include <X11/X.h>
#include <X11/Xutil.h>
#include <cairo.h>
#include <cairo-xlib.h>
#include <chrono>
#include <thread>
void draw(cairo_t *cr) {
cairo_set_source_rgba(cr, 1.0, 0.0, 0.0, 0.5);
cairo_rectangle(cr, 0, 0, 200, 200);
cairo_fill(cr);
}
int main() {
Display *d = XOpenDisplay(NULL);
Window root = DefaultRootWindow(d);
int default_screen = XDefaultScreen(d);
// these two lines are really all you need
XSetWindowAttributes attrs;
attrs.override_redirect = true;
XVisualInfo vinfo;
if (!XMatchVisualInfo(d, DefaultScreen(d), 32, TrueColor, &vinfo)) {
printf("No visual found supporting 32 bit color, terminating\n");
exit(EXIT_FAILURE);
}
// these next three lines add 32 bit depth, remove if you dont need and change the flags below
attrs.colormap = XCreateColormap(d, root, vinfo.visual, AllocNone);
attrs.background_pixel = 0;
attrs.border_pixel = 0;
// Window XCreateWindow(
// Display *display, Window parent,
// int x, int y, unsigned int width, unsigned int height, unsigned int border_width,
// int depth, unsigned int class,
// Visual *visual,
// unsigned long valuemask, XSetWindowAttributes *attributes
// );
Window overlay = XCreateWindow(
d, root,
0, 0, 200, 200, 0,
vinfo.depth, InputOutput,
vinfo.visual,
CWOverrideRedirect | CWColormap | CWBackPixel | CWBorderPixel, &attrs
);
XMapWindow(d, overlay);
cairo_surface_t* surf = cairo_xlib_surface_create(d, overlay,
vinfo.visual,
200, 200);
cairo_t* cr = cairo_create(surf);
draw(cr);
XFlush(d);
std::this_thread::sleep_for(std::chrono::milliseconds(10000));
cairo_destroy(cr);
cairo_surface_destroy(surf);
XUnmapWindow(d, overlay);
XCloseDisplay(d);
return 0;
}
我继续并添加了32位深度,但是您可以理解。 如果需要,可以将其删除。
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