feat: add a new awesome feature

src/Canvas.cpp

@@ -1,10 +1,16 @@
 #include "Canvas.h"
 
 Canvas::Canvas()
-	:Control(0, 0, 100, 100) {}
+	:Control(0, 0, 100, 100)
+{
+	this->id = "Canvas";
+}
 
 Canvas::Canvas(int x, int y, int width, int height)
-	:Control(x, y, width, height) {}
+	:Control(x, y, width, height) 
+{
+	this->id = "Canvas";
+}
 
 void Canvas::clearAllControls()
 {
@@ -14,14 +20,17 @@ void Canvas::clearAllControls()
 
 void Canvas::draw()
 {
-	if (!dirty && !show)return;
+	if (!dirty||!show)return;
 	saveStyle();
 
 	setlinecolor(canvasBorderClor);//设置线色
 	setfillcolor(canvasBkClor);//设置填充色
 	setfillstyle((int)canvasFillMode);//设置填充模式
 	setlinestyle((int)canvasLineStyle, canvaslinewidth);
-	
+	if ((saveBkX != this->x) || (saveBkY != this->y) || (!hasSnap) || (saveWidth != this->width) || (saveHeight != this->height) || !saveBkImage)
+		saveBackground(this->x, this->y, this->width, this->height);
+	// 恢复背景（清除旧内容）
+	restBackground();
 	//根据画布形状绘制
 	switch (shape)
 	{
@@ -51,16 +60,22 @@ void Canvas::draw()
 
 bool Canvas::handleEvent(const ExMessage& msg)
 {
-	if(!show)return false;
+	if (!show)return false;
+	bool consumed = false;
+	bool anyDirty = false;
 
-    for (auto it = controls.rbegin(); it != controls.rend(); ++it)
-        if ((*it)->handleEvent(msg))
-            return true; // 事件被消费短路传递，立即返回true 否则返回false
-    return false;
+	for (auto it = controls.rbegin(); it != controls.rend(); ++it)
+	{
+		consumed |= it->get()->handleEvent(msg);
+		if (it->get()->isDirty()) anyDirty = true;
+	}
+	if (anyDirty) requestRepaint();
+	return consumed;
 }
 
 void Canvas::addControl(std::unique_ptr<Control> control)
 {
+	control->setParent(this);
 	controls.push_back(std::move(control));
 	dirty = true;
 }
@@ -117,5 +132,32 @@ void Canvas::setLinewidth(int width)
 	dirty = true;
 }
 
+void Canvas::setIsVisible(bool visible)
+{
+	this->show = visible;
+	dirty = true;
+	for (auto& control : controls)
+	{
+		control->setIsVisible(visible);
+		control->setDirty(true);
+	}
+	if (!visible)
+		this->updateBackground();
+}
+
+void Canvas::setDirty(bool dirty)
+{
+	this->dirty = dirty;
+	for(auto& control : controls)
+		control->setDirty(dirty);
+}
+
+void Canvas::onWindowResize()
+{
+	Control::onWindowResize();          // 先处理自己
+	for (auto& ch : controls)          // 再转发给所有子控件
+		ch->onWindowResize();
+}
+