[FFmpeg-devel] [PATCH v5] avdevice/xcbgrab: Add select_region option
Omar Emara
mail at OmarEmara.dev
Wed Jul 8 12:55:29 EEST 2020
This patch adds a select_region option to the xcbgrab input device.
If set to 1, the user will be prompted to select the grabbing area
graphically by clicking and dragging. A rectangle will be drawn to
mark the grabbing area. A single click with no dragging will select
the whole screen. The option overwrites the video_size, grab_x, and
grab_y options if set by the user.
For testing, just set the select_region option as follows:
ffmpeg -f x11grab -select_region 1 -i :0.0 output.mp4
The drawing happens directly on the root window using standard rubber
banding techniques, so it is very efficient and doesn't depend on any
X extensions or compositors.
Signed-off-by: Omar Emara <mail at OmarEmara.dev>
---
doc/indevs.texi | 7 +++
libavdevice/xcbgrab.c | 126 ++++++++++++++++++++++++++++++++++++++++++
2 files changed, 133 insertions(+)
diff --git a/doc/indevs.texi b/doc/indevs.texi
index 6f5afaf344..b5df111801 100644
--- a/doc/indevs.texi
+++ b/doc/indevs.texi
@@ -1478,6 +1478,13 @@ ffmpeg -f x11grab -framerate 25 -video_size cif -i :0.0+10,20 out.mpg
@subsection Options
@table @option
+ at item select_region
+Specify whether to select the grabbing area graphically using the pointer.
+A value of @code{1} prompts the user to select the grabbing area graphically
+by clicking and dragging. A single click with no dragging will select the
+whole screen. This option overwrites the @var{video_size}, @var{grab_x},
+and @var{grab_y} options. Default value is @code{0}.
+
@item draw_mouse
Specify whether to draw the mouse pointer. A value of @code{0} specifies
not to draw the pointer. Default value is @code{1}.
diff --git a/libavdevice/xcbgrab.c b/libavdevice/xcbgrab.c
index 6f6b2dbf15..04f888c142 100644
--- a/libavdevice/xcbgrab.c
+++ b/libavdevice/xcbgrab.c
@@ -22,6 +22,7 @@
#include "config.h"
#include <stdlib.h>
+#include <string.h>
#include <xcb/xcb.h>
#if CONFIG_LIBXCB_XFIXES
@@ -69,6 +70,7 @@ typedef struct XCBGrabContext {
int show_region;
int region_border;
int centered;
+ int select_region;
const char *framerate;
@@ -92,6 +94,7 @@ static const AVOption options[] = {
{ "centered", "Keep the mouse pointer at the center of grabbing region when following.", 0, AV_OPT_TYPE_CONST, { .i64 = -1 }, INT_MIN, INT_MAX, D, "follow_mouse" },
{ "show_region", "Show the grabbing region.", OFFSET(show_region), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, 1, D },
{ "region_border", "Set the region border thickness.", OFFSET(region_border), AV_OPT_TYPE_INT, { .i64 = 3 }, 1, 128, D },
+ { "select_region", "Select the grabbing region graphically using the pointer.", OFFSET(select_region), AV_OPT_TYPE_BOOL, { .i64 = 0 }, 0, 1, D },
{ NULL },
};
@@ -668,6 +671,121 @@ static void setup_window(AVFormatContext *s)
draw_rectangle(s);
}
+#define CROSSHAIR_CURSOR 34
+
+static xcb_rectangle_t rectangle_from_corners(xcb_point_t *corner_a,
+ xcb_point_t *corner_b)
+{
+ xcb_rectangle_t rectangle;
+ rectangle.x = FFMIN(corner_a->x, corner_b->x);
+ rectangle.y = FFMIN(corner_a->y, corner_b->y);
+ rectangle.width = FFABS(corner_a->x - corner_b->x);
+ rectangle.height = FFABS(corner_a->y - corner_b->y);
+ return rectangle;
+}
+
+static int select_region(AVFormatContext *s)
+{
+ XCBGrabContext *c = s->priv_data;
+ xcb_connection_t *conn = c->conn;
+ xcb_screen_t *screen = c->screen;
+
+ int ret = 0;
+ int done = 0;
+ int was_pressed = 0;
+ xcb_cursor_t cursor;
+ xcb_font_t cursor_font;
+ xcb_point_t press_position;
+ xcb_generic_event_t *event;
+ xcb_rectangle_t rectangle = {0};
+ xcb_grab_pointer_reply_t *reply;
+ xcb_grab_pointer_cookie_t cookie;
+
+ xcb_window_t root_window = screen->root;
+ xcb_gcontext_t gc = xcb_generate_id(conn);
+ uint32_t mask = XCB_GC_FUNCTION | XCB_GC_SUBWINDOW_MODE;
+ uint32_t values[] = {XCB_GX_INVERT,
+ XCB_SUBWINDOW_MODE_INCLUDE_INFERIORS};
+ xcb_create_gc(conn, gc, root_window, mask, values);
+
+ cursor_font = xcb_generate_id(conn);
+ xcb_open_font(conn, cursor_font, strlen("cursor"), "cursor");
+ cursor = xcb_generate_id(conn);
+ xcb_create_glyph_cursor(conn, cursor, cursor_font, cursor_font,
+ CROSSHAIR_CURSOR, CROSSHAIR_CURSOR + 1, 0, 0, 0,
+ 0xFFFF, 0xFFFF, 0xFFFF);
+ cookie = xcb_grab_pointer(conn, 0, root_window,
+ XCB_EVENT_MASK_BUTTON_PRESS |
+ XCB_EVENT_MASK_BUTTON_RELEASE |
+ XCB_EVENT_MASK_BUTTON_MOTION,
+ XCB_GRAB_MODE_ASYNC, XCB_GRAB_MODE_ASYNC,
+ root_window, cursor, XCB_CURRENT_TIME);
+ reply = xcb_grab_pointer_reply(conn, cookie, NULL);
+ if (!reply || reply->status != XCB_GRAB_STATUS_SUCCESS) {
+ av_log(s, AV_LOG_ERROR,
+ "Failed to select region. Could not grab pointer.\n");
+ ret = AVERROR(EIO);
+ free(reply);
+ goto fail;
+ }
+ free(reply);
+
+ xcb_grab_server(conn);
+
+ while (!done && (event = xcb_wait_for_event(conn))) {
+ switch (event->response_type & ~0x80) {
+ case XCB_BUTTON_PRESS: {
+ xcb_button_press_event_t *press = (xcb_button_press_event_t *)event;
+ press_position = (xcb_point_t){press->event_x, press->event_y};
+ rectangle.x = press_position.x;
+ rectangle.y = press_position.y;
+ xcb_poly_rectangle(conn, root_window, gc, 1, &rectangle);
+ was_pressed = 1;
+ break;
+ }
+ case XCB_MOTION_NOTIFY: {
+ xcb_motion_notify_event_t *motion =
+ (xcb_motion_notify_event_t *)event;
+ if (was_pressed) {
+ xcb_point_t cursor_position = {motion->event_x,
+ motion->event_y};
+ xcb_poly_rectangle(conn, root_window, gc, 1, &rectangle);
+ rectangle = rectangle_from_corners(
+ &press_position, &cursor_position);
+ xcb_poly_rectangle(conn, root_window, gc, 1, &rectangle);
+ }
+ break;
+ }
+ case XCB_BUTTON_RELEASE: {
+ xcb_poly_rectangle(conn, root_window, gc, 1, &rectangle);
+ done = 1;
+ break;
+ }
+ default:
+ break;
+ }
+ xcb_flush(conn);
+ free(event);
+ }
+ c->width = rectangle.width;
+ c->height = rectangle.height;
+ if (c->width && c->height) {
+ c->x = rectangle.x;
+ c->y = rectangle.y;
+ } else {
+ c->x = 0;
+ c->y = 0;
+ }
+ xcb_ungrab_server(conn);
+ xcb_ungrab_pointer(conn, XCB_CURRENT_TIME);
+
+fail:
+ xcb_free_cursor(conn, cursor);
+ xcb_close_font(conn, cursor_font);
+ xcb_free_gc(conn, gc);
+ return ret;
+}
+
static av_cold int xcbgrab_read_header(AVFormatContext *s)
{
XCBGrabContext *c = s->priv_data;
@@ -702,6 +820,14 @@ static av_cold int xcbgrab_read_header(AVFormatContext *s)
return AVERROR(EIO);
}
+ if (c->select_region) {
+ ret = select_region(s);
+ if (ret < 0) {
+ xcbgrab_read_close(s);
+ return ret;
+ }
+ }
+
ret = create_stream(s);
if (ret < 0) {
--
2.27.0
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