透明绘制复合图层而不是重绘

发布于 2024-09-19 08:01:35 字数 1030 浏览 3 评论 0原文

我有一个自定义控件，在其中重写以下方法来创建透明背景：

    protected override CreateParams CreateParams
    {
        get
        {
            CreateParams cp = base.CreateParams;
            cp.ExStyle |= 0x20;
            return cp;
        }
    }

在绘制方法上，我执行以下操作：

    protected override void OnPaint(PaintEventArgs p)
    {
        base.OnPaint(p);
        Graphics e = p.Graphics;
        this.Size = Resources.CenterButtonHover.Size;
        if (mousedown)
        {
            e.DrawImage(Resources.CenterButtonDown, new Point(0, 0));
        }
        else if (hover)
        {
            e.DrawImage(Resources.CenterButtonHover, new Point(0, 0));
        }
        else
        {
            e.DrawImage(Resources.CenterButtonNormal, new Point(4, 4));
        }
        e.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.AntiAlias;
    }

以及在调用 this.Invalidate 时的各种鼠标事件上。

透明度已正确渲染，但每次渲染时都会在上次渲染的基础上进行渲染，而不是重新绘制。这导致发光变得越来越强烈，直到变成一个大斑点。我该如何解决这个问题？

原文

I have a custom control in which I am overriding the following method to create a transparent background:

    protected override CreateParams CreateParams
    {
        get
        {
            CreateParams cp = base.CreateParams;
            cp.ExStyle |= 0x20;
            return cp;
        }
    }

On the paint method, im doing this:

    protected override void OnPaint(PaintEventArgs p)
    {
        base.OnPaint(p);
        Graphics e = p.Graphics;
        this.Size = Resources.CenterButtonHover.Size;
        if (mousedown)
        {
            e.DrawImage(Resources.CenterButtonDown, new Point(0, 0));
        }
        else if (hover)
        {
            e.DrawImage(Resources.CenterButtonHover, new Point(0, 0));
        }
        else
        {
            e.DrawImage(Resources.CenterButtonNormal, new Point(4, 4));
        }
        e.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.AntiAlias;
    }

And on the various mouse events in calling this.Invalidate.

The transparency is being rendered correctly, but every time it renders it renders over top of the last render instead of redrawing. This causes the glow to get more and more intense until its just a big blob. How do I fix this?

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暮光沉寂 2024-09-26 08:01:35

我通过保留一个布尔值来解决这个问题，以确定在重新绘制之前是否需要删除渐变。

        if (needsreset)
        {
            this.SuspendLayout();
            this.Region = new Region(this.ClientRectangle);
            needsreset = false;
            return;
        }

I solved it by keeping a bool as to whether or not there was a gradient that needed to be removed or not before re-drawing.

        if (needsreset)
        {
            this.SuspendLayout();
            this.Region = new Region(this.ClientRectangle);
            needsreset = false;
            return;
        }

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