Draw cursor in window capture

1 files changed, 127 insertions, 0 deletions

diff --git a/src/cursor.c b/src/cursor.c
new file mode 100644
index 0000000..737c33b
--- /dev/null
+++ b/src/cursor.c
@@ -0,0 +1,127 @@
+#include "../include/cursor.h"
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <assert.h>
+
+#include <X11/extensions/Xfixes.h>
+
+static bool gsr_cursor_set_from_x11_cursor_image(gsr_cursor *self, XFixesCursorImage *x11_cursor_image) {
+    uint8_t *cursor_data = NULL;
+    uint8_t *out = NULL;
+
+    if(!x11_cursor_image)
+        goto err;
+        
+    if(!x11_cursor_image->pixels)
+        goto err;
+
+    self->hotspot.x = x11_cursor_image->xhot;
+    self->hotspot.y = x11_cursor_image->yhot;
+    self->egl->glBindTexture(GL_TEXTURE_2D, self->texture_id);
+
+    self->size.x = x11_cursor_image->width;
+    self->size.y = x11_cursor_image->height;
+    const unsigned long *pixels = x11_cursor_image->pixels;
+    cursor_data = malloc(self->size.x * self->size.y * 4);
+    if(!cursor_data)
+        goto err;
+    out = cursor_data;
+    /* Un-premultiply alpha */
+    for(int y = 0; y < self->size.y; ++y) {
+        for(int x = 0; x < self->size.x; ++x) {
+            uint32_t pixel = *pixels++;
+            uint8_t *in = (uint8_t*)&pixel;
+            uint8_t alpha = in[3];
+            if(alpha == 0)
+                alpha = 1;
+
+            *out++ = (unsigned)*in++ * 255/alpha;
+            *out++ = (unsigned)*in++ * 255/alpha;
+            *out++ = (unsigned)*in++ * 255/alpha;
+            *out++ = *in++;
+        }
+    }
+
+    self->egl->glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, self->size.x, self->size.y, 0, GL_RGBA, GL_UNSIGNED_BYTE, cursor_data);
+    free(cursor_data);
+
+    self->egl->glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+    self->egl->glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+    self->egl->glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+    self->egl->glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+
+    self->egl->glBindTexture(GL_TEXTURE_2D, 0);
+    XFree(x11_cursor_image);
+    return true;
+
+    err:
+    self->egl->glBindTexture(GL_TEXTURE_2D, 0);
+    if(x11_cursor_image)
+        XFree(x11_cursor_image);
+    return false;
+}
+
+int gsr_cursor_init(gsr_cursor *self, gsr_egl *egl, Display *display) {
+    int x_fixes_error_base = 0;
+
+    assert(egl);
+    assert(display);
+    memset(self, 0, sizeof(*self));
+    self->egl = egl;
+    self->display = display;
+
+    self->x_fixes_event_base = 0;
+    if(!XFixesQueryExtension(self->display, &self->x_fixes_event_base, &x_fixes_error_base)) {
+        fprintf(stderr, "gsr error: gsr_cursor_init: your X11 server is missing the XFixes extension\n");
+        gsr_cursor_deinit(self);
+        return -1;
+    }
+
+    self->egl->glGenTextures(1, &self->texture_id);
+
+    XFixesSelectCursorInput(self->display, DefaultRootWindow(self->display), XFixesDisplayCursorNotifyMask);
+    gsr_cursor_set_from_x11_cursor_image(self, XFixesGetCursorImage(self->display));
+    self->cursor_image_set = true;
+
+    return 0;
+}
+
+void gsr_cursor_deinit(gsr_cursor *self) {
+    if(!self->egl)
+        return;
+
+    if(self->texture_id) {
+        self->egl->glDeleteTextures(1, &self->texture_id);
+        self->texture_id = 0;
+    }
+
+    XFixesSelectCursorInput(self->display, DefaultRootWindow(self->display), 0);
+
+    self->display = NULL;
+    self->egl = NULL;
+}
+
+void gsr_cursor_update(gsr_cursor *self, XEvent *xev) {
+    if(xev->type == self->x_fixes_event_base + XFixesCursorNotify) {
+        XFixesCursorNotifyEvent *cursor_notify_event = (XFixesCursorNotifyEvent*)xev;
+        if(cursor_notify_event->subtype == XFixesDisplayCursorNotify && cursor_notify_event->window == DefaultRootWindow(self->display)) {
+            self->cursor_image_set = true;
+            gsr_cursor_set_from_x11_cursor_image(self, XFixesGetCursorImage(self->display));
+        }
+    }
+
+    if(!self->cursor_image_set) {
+        self->cursor_image_set = true;
+        gsr_cursor_set_from_x11_cursor_image(self, XFixesGetCursorImage(self->display));
+    }
+}
+
+void gsr_cursor_tick(gsr_cursor *self, Window relative_to) {
+    /* TODO: Use XInput2 instead. However that doesn't work when the pointer is grabbed. Maybe check for focused window change and XSelectInput PointerMask */
+    Window dummy_window;
+    int dummy_i;
+    unsigned int dummy_u;
+    XQueryPointer(self->display, relative_to, &dummy_window, &dummy_window, &dummy_i, &dummy_i, &self->position.x, &self->position.y, &dummy_u);
+}