Fix Color Picking

With the 4.x-introduction of Windows the previous method for
color picking was no longer working.

This PR uses the following approach to reintroduce color-picking.
When the Color-Picking-Button is pressed, a quasi-screenshot of the
Window-content is created and displayed in a new Popup-Window.
This new Window allows selecting colors by Mouse-Click.
A Preview of the targeted Color is also displayed.

5 files changed, 107 insertions, 52 deletions

diff --git a/scene/gui/color_picker.cpp b/scene/gui/color_picker.cpp
index da29bc823f..eb8938fe97 100644
--- a/scene/gui/color_picker.cpp
+++ b/scene/gui/color_picker.cpp
@@ -31,10 +31,12 @@
 #include "color_picker.h"
 
 #include "core/input/input.h"
+#include "core/io/image.h"
 #include "core/math/color.h"
 #include "core/os/keyboard.h"
 #include "core/os/os.h"
 #include "scene/gui/color_mode.h"
+#include "servers/display_server.h"
 #include "thirdparty/misc/ok_color.h"
 #include "thirdparty/misc/ok_color_shader.h"
 
@@ -90,8 +92,8 @@ void ColorPicker::_notification(int p_what) {
 		} break;
 
 		case NOTIFICATION_WM_CLOSE_REQUEST: {
-			if (screen != nullptr && screen->is_visible()) {
-				screen->hide();
+			if (picker_window != nullptr && picker_window->is_visible()) {
+				picker_window->hide();
 			}
 		} break;
 	}
@@ -1372,30 +1374,26 @@ void ColorPicker::_recent_preset_pressed(const bool p_pressed, ColorPresetButton
 	emit_signal(SNAME("color_changed"), p_preset->get_preset_color());
 }
 
-void ColorPicker::_screen_input(const Ref<InputEvent> &p_event) {
+void ColorPicker::_picker_texture_input(const Ref<InputEvent> &p_event) {
 	if (!is_inside_tree()) {
 		return;
 	}
 
 	Ref<InputEventMouseButton> bev = p_event;
 	if (bev.is_valid() && bev->get_button_index() == MouseButton::LEFT && !bev->is_pressed()) {
+		set_pick_color(picker_color);
 		emit_signal(SNAME("color_changed"), color);
-		screen->hide();
+		picker_window->hide();
 	}
 
 	Ref<InputEventMouseMotion> mev = p_event;
 	if (mev.is_valid()) {
-		Viewport *r = get_tree()->get_root();
-		if (!r->get_visible_rect().has_point(mev->get_global_position())) {
-			return;
-		}
-
-		Ref<Image> img = r->get_texture()->get_image();
+		Ref<Image> img = picker_texture_rect->get_texture()->get_image();
 		if (img.is_valid() && !img->is_empty()) {
-			Vector2 ofs = mev->get_global_position();
-			Color c = img->get_pixel(ofs.x, ofs.y);
-
-			set_pick_color(c);
+			Vector2 ofs = mev->get_position();
+			picker_color = img->get_pixel(ofs.x, ofs.y);
+			picker_preview_style_box->set_bg_color(picker_color);
+			picker_preview_label->set_self_modulate(picker_color.get_luminance() < 0.5 ? Color(1.0f, 1.0f, 1.0f) : Color(0.0f, 0.0f, 0.0f));
 		}
 	}
 }
@@ -1409,27 +1407,79 @@ void ColorPicker::_add_preset_pressed() {
 	emit_signal(SNAME("preset_added"), color);
 }
 
-void ColorPicker::_screen_pick_pressed() {
+void ColorPicker::_pick_button_pressed() {
 	if (!is_inside_tree()) {
 		return;
 	}
 
-	Viewport *r = get_tree()->get_root();
-	if (!screen) {
-		screen = memnew(Control);
-		r->add_child(screen);
-		screen->set_as_top_level(true);
-		screen->set_anchors_and_offsets_preset(Control::PRESET_FULL_RECT);
-		screen->set_default_cursor_shape(CURSOR_POINTING_HAND);
-		screen->connect("gui_input", callable_mp(this, &ColorPicker::_screen_input));
-		// It immediately toggles off in the first press otherwise.
-		screen->call_deferred(SNAME("connect"), "hidden", Callable(btn_pick, "set_pressed").bind(false));
+	if (!picker_window) {
+		picker_window = memnew(Popup);
+		picker_window->hide();
+		picker_window->set_transient(true);
+		add_child(picker_window);
+
+		picker_texture_rect = memnew(TextureRect);
+		picker_texture_rect->set_anchors_preset(Control::PRESET_FULL_RECT);
+		picker_window->add_child(picker_texture_rect);
+		picker_texture_rect->set_default_cursor_shape(CURSOR_POINTING_HAND);
+		picker_texture_rect->connect(SNAME("gui_input"), callable_mp(this, &ColorPicker::_picker_texture_input));
+
+		picker_preview = memnew(Panel);
+		picker_preview->set_anchors_preset(Control::PRESET_CENTER_TOP);
+		picker_preview->set_mouse_filter(MOUSE_FILTER_IGNORE);
+		picker_window->add_child(picker_preview);
+
+		picker_preview_label = memnew(Label);
+		picker_preview->set_anchors_preset(Control::PRESET_CENTER_TOP);
+		picker_preview_label->set_text("Color Picking active");
+		picker_preview->add_child(picker_preview_label);
+
+		picker_preview_style_box = (Ref<StyleBoxFlat>)memnew(StyleBoxFlat);
+		picker_preview_style_box->set_bg_color(Color(1.0, 1.0, 1.0));
+		picker_preview->add_theme_style_override("panel", picker_preview_style_box);
+	}
+
+	Rect2i screen_rect;
+	if (picker_window->is_embedded()) {
+		screen_rect = picker_window->get_embedder()->get_visible_rect();
+		picker_window->set_position(Point2i());
+		picker_texture_rect->set_texture(ImageTexture::create_from_image(picker_window->get_embedder()->get_texture()->get_image()));
 	} else {
-		screen->show();
+		screen_rect = picker_window->get_parent_rect();
+		picker_window->set_position(screen_rect.position);
+
+		Ref<Image> target_image = Image::create_empty(screen_rect.size.x, screen_rect.size.y, false, Image::FORMAT_RGB8);
+		DisplayServer *ds = DisplayServer::get_singleton();
+
+		// Add the Texture of each Window to the Image.
+		Vector<DisplayServer::WindowID> wl = ds->get_window_list();
+		// FIXME: sort windows by visibility.
+		for (int index = 0; index < wl.size(); index++) {
+			DisplayServer::WindowID wid = wl[index];
+			if (wid == DisplayServer::INVALID_WINDOW_ID) {
+				continue;
+			}
+
+			ObjectID woid = DisplayServer::get_singleton()->window_get_attached_instance_id(wid);
+			if (woid == ObjectID()) {
+				continue;
+			}
+
+			Window *w = Object::cast_to<Window>(ObjectDB::get_instance(woid));
+			Ref<Image> img = w->get_texture()->get_image();
+			if (!img.is_valid() || img->is_empty()) {
+				continue;
+			}
+			img->convert(Image::FORMAT_RGB8);
+			target_image->blit_rect(img, Rect2i(Point2i(0, 0), img->get_size()), w->get_position());
+		}
+
+		picker_texture_rect->set_texture(ImageTexture::create_from_image(target_image));
 	}
-	screen->move_to_front();
-	// TODO: show modal no longer works, needs to be converted to a popup.
-	//screen->show_modal();
+
+	picker_window->set_size(screen_rect.size);
+	picker_preview->set_size(screen_rect.size / 10.0); // 10% of size in each axis.
+	picker_window->popup();
 }
 
 void ColorPicker::_html_focus_exit() {
@@ -1595,9 +1645,8 @@ ColorPicker::ColorPicker() {
 
 	btn_pick = memnew(Button);
 	sample_hbc->add_child(btn_pick);
-	btn_pick->set_toggle_mode(true);
-	btn_pick->set_tooltip_text(RTR("Pick a color from the editor window."));
-	btn_pick->connect("pressed", callable_mp(this, &ColorPicker::_screen_pick_pressed));
+	btn_pick->set_tooltip_text(RTR("Pick a color from the application window."));
+	btn_pick->connect(SNAME("pressed"), callable_mp(this, &ColorPicker::_pick_button_pressed));
 
 	sample = memnew(TextureRect);
 	sample_hbc->add_child(sample);
diff --git a/scene/gui/color_picker.h b/scene/gui/color_picker.h
index f7578612cd..d02c3278e6 100644
--- a/scene/gui/color_picker.h
+++ b/scene/gui/color_picker.h
@@ -40,6 +40,7 @@
 #include "scene/gui/line_edit.h"
 #include "scene/gui/menu_button.h"
 #include "scene/gui/option_button.h"
+#include "scene/gui/panel.h"
 #include "scene/gui/popup.h"
 #include "scene/gui/separator.h"
 #include "scene/gui/slider.h"
@@ -111,7 +112,12 @@ private:
 
 	Vector<ColorMode *> modes;
 
-	Control *screen = nullptr;
+	Popup *picker_window = nullptr;
+	TextureRect *picker_texture_rect = nullptr;
+	Panel *picker_preview = nullptr;
+	Label *picker_preview_label = nullptr;
+	Ref<StyleBoxFlat> picker_preview_style_box;
+	Color picker_color;
 	Control *uv_edit = nullptr;
 	Control *w_edit = nullptr;
 	AspectRatioContainer *wheel_edit = nullptr;
@@ -211,10 +217,10 @@ private:
 	void _line_edit_input(const Ref<InputEvent> &p_event);
 	void _preset_input(const Ref<InputEvent> &p_event, const Color &p_color);
 	void _recent_preset_pressed(const bool pressed, ColorPresetButton *p_preset);
-	void _screen_input(const Ref<InputEvent> &p_event);
+	void _picker_texture_input(const Ref<InputEvent> &p_event);
 	void _text_changed(const String &p_new_text);
 	void _add_preset_pressed();
-	void _screen_pick_pressed();
+	void _pick_button_pressed();
 	void _html_focus_exit();
 
 	inline int _get_preset_size();
diff --git a/scene/main/viewport.cpp b/scene/main/viewport.cpp
index a1e7555a5d..5f969c98a2 100644
--- a/scene/main/viewport.cpp
+++ b/scene/main/viewport.cpp
@@ -1311,7 +1311,7 @@ void Viewport::_gui_show_tooltip() {
 	Window *window = gui.tooltip_popup->get_parent_visible_window();
 	Rect2i vr;
 	if (gui.tooltip_popup->is_embedded()) {
-		vr = gui.tooltip_popup->_get_embedder()->get_visible_rect();
+		vr = gui.tooltip_popup->get_embedder()->get_visible_rect();
 	} else {
 		vr = window->get_usable_parent_rect();
 	}
@@ -1832,7 +1832,7 @@ void Viewport::_gui_input_event(Ref<InputEvent> p_event) {
 				Window *w = Object::cast_to<Window>(this);
 				if (w) {
 					if (w->is_embedded()) {
-						embedder = w->_get_embedder();
+						embedder = w->get_embedder();
 
 						viewport_pos = get_final_transform().xform(mpos) + w->get_position(); // To parent coords.
 					}
diff --git a/scene/main/window.cpp b/scene/main/window.cpp
index 44df648552..fbacb252c9 100644
--- a/scene/main/window.cpp
+++ b/scene/main/window.cpp
@@ -485,7 +485,7 @@ void Window::set_ime_position(const Point2i &p_pos) {
 bool Window::is_embedded() const {
 	ERR_FAIL_COND_V(!is_inside_tree(), false);
 
-	return _get_embedder() != nullptr;
+	return get_embedder() != nullptr;
 }
 
 bool Window::is_in_edited_scene_root() const {
@@ -704,7 +704,7 @@ void Window::set_visible(bool p_visible) {
 	// Stop any queued resizing, as the window will be resized right now.
 	updating_child_controls = false;
 
-	Viewport *embedder_vp = _get_embedder();
+	Viewport *embedder_vp = get_embedder();
 
 	if (!embedder_vp) {
 		if (!p_visible && window_id != DisplayServer::INVALID_WINDOW_ID) {
@@ -1051,7 +1051,7 @@ void Window::_update_window_callbacks() {
 	DisplayServer::get_singleton()->window_set_drop_files_callback(callable_mp(this, &Window::_window_drop_files), window_id);
 }
 
-Viewport *Window::_get_embedder() const {
+Viewport *Window::get_embedder() const {
 	Viewport *vp = get_parent_viewport();
 
 	while (vp) {
@@ -1086,7 +1086,7 @@ void Window::_notification(int p_what) {
 		case NOTIFICATION_ENTER_TREE: {
 			bool embedded = false;
 			{
-				embedder = _get_embedder();
+				embedder = get_embedder();
 				if (embedder) {
 					embedded = true;
 					if (!visible) {
@@ -1425,7 +1425,7 @@ void Window::popup_centered_clamped(const Size2i &p_size, float p_fallback_ratio
 	Rect2 parent_rect;
 
 	if (is_embedded()) {
-		parent_rect = _get_embedder()->get_visible_rect();
+		parent_rect = get_embedder()->get_visible_rect();
 	} else {
 		DisplayServer::WindowID parent_id = get_parent_visible_window()->get_window_id();
 		int parent_screen = DisplayServer::get_singleton()->window_get_current_screen(parent_id);
@@ -1453,7 +1453,7 @@ void Window::popup_centered(const Size2i &p_minsize) {
 	Rect2 parent_rect;
 
 	if (is_embedded()) {
-		parent_rect = _get_embedder()->get_visible_rect();
+		parent_rect = get_embedder()->get_visible_rect();
 	} else {
 		DisplayServer::WindowID parent_id = get_parent_visible_window()->get_window_id();
 		int parent_screen = DisplayServer::get_singleton()->window_get_current_screen(parent_id);
@@ -1479,7 +1479,7 @@ void Window::popup_centered_ratio(float p_ratio) {
 	Rect2 parent_rect;
 
 	if (is_embedded()) {
-		parent_rect = _get_embedder()->get_visible_rect();
+		parent_rect = get_embedder()->get_visible_rect();
 	} else {
 		DisplayServer::WindowID parent_id = get_parent_visible_window()->get_window_id();
 		int parent_screen = DisplayServer::get_singleton()->window_get_current_screen(parent_id);
@@ -1500,7 +1500,7 @@ void Window::popup_centered_ratio(float p_ratio) {
 void Window::popup(const Rect2i &p_screen_rect) {
 	emit_signal(SNAME("about_to_popup"));
 
-	if (!_get_embedder() && get_flag(FLAG_POPUP)) {
+	if (!get_embedder() && get_flag(FLAG_POPUP)) {
 		// Send a focus-out notification when opening a Window Manager Popup.
 		SceneTree *scene_tree = get_tree();
 		if (scene_tree) {
@@ -1536,7 +1536,7 @@ void Window::popup(const Rect2i &p_screen_rect) {
 
 	Rect2i parent_rect;
 	if (is_embedded()) {
-		parent_rect = _get_embedder()->get_visible_rect();
+		parent_rect = get_embedder()->get_visible_rect();
 	} else {
 		int screen_id = DisplayServer::get_singleton()->window_get_current_screen(get_window_id());
 		parent_rect = DisplayServer::get_singleton()->screen_get_usable_rect(screen_id);
@@ -1578,7 +1578,7 @@ Rect2i Window::get_usable_parent_rect() const {
 	ERR_FAIL_COND_V(!is_inside_tree(), Rect2());
 	Rect2i parent_rect;
 	if (is_embedded()) {
-		parent_rect = _get_embedder()->get_visible_rect();
+		parent_rect = get_embedder()->get_visible_rect();
 	} else {
 		const Window *w = is_visible() ? this : get_parent_visible_window();
 		//find a parent that can contain us
@@ -2145,9 +2145,9 @@ Transform2D Window::get_final_transform() const {
 
 Transform2D Window::get_screen_transform_internal(bool p_absolute_position) const {
 	Transform2D embedder_transform;
-	if (_get_embedder()) {
+	if (get_embedder()) {
 		embedder_transform.translate_local(get_position());
-		embedder_transform = _get_embedder()->get_screen_transform_internal(p_absolute_position) * embedder_transform;
+		embedder_transform = get_embedder()->get_screen_transform_internal(p_absolute_position) * embedder_transform;
 	} else if (p_absolute_position) {
 		embedder_transform.translate_local(get_position());
 	}
@@ -2161,8 +2161,8 @@ Transform2D Window::get_popup_base_transform() const {
 	Transform2D popup_base_transform;
 	popup_base_transform.set_origin(get_position());
 	popup_base_transform *= get_final_transform();
-	if (_get_embedder()) {
-		return _get_embedder()->get_popup_base_transform() * popup_base_transform;
+	if (get_embedder()) {
+		return get_embedder()->get_popup_base_transform() * popup_base_transform;
 	}
 	return popup_base_transform;
 }
diff --git a/scene/main/window.h b/scene/main/window.h
index 5359c37e9a..40b629ed11 100644
--- a/scene/main/window.h
+++ b/scene/main/window.h
@@ -192,7 +192,6 @@ private:
 	Ref<Shortcut> debugger_stop_shortcut;
 
 protected:
-	Viewport *_get_embedder() const;
 	virtual Rect2i _popup_adjust_rect() const { return Rect2i(); }
 
 	virtual void _update_theme_item_cache();
@@ -278,6 +277,7 @@ public:
 	void set_ime_position(const Point2i &p_pos);
 
 	bool is_embedded() const;
+	Viewport *get_embedder() const;
 
 	void set_content_scale_size(const Size2i &p_size);
 	Size2i get_content_scale_size() const;