Question

我正在设计一个与VB.NET中的MS Paint具有相同功能的程序。下面的代码允许我成功地单击并拖动以在图片框上绘制选择矩形，但它看起来很滞后（特别是与MS Paint本身相比）。有没有更有效的方法呢？

Public DrawCapture As Boolean = False
Public DrawCaptureOrigin As Point
Public DrawCaptureRectangle As Rectangle

Private Sub PictureBox1_MouseDown(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles PictureBox1.MouseDown
    DrawCapture = True
    DrawCaptureOrigin = e.Location
    DrawCaptureRectangle = New Rectangle(e.Location, New Point(1, 1))
End Sub

Private Sub PictureBox1_MouseMove(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles PictureBox1.MouseMove
    Dim curX As Integer = e.Location.X, curY As Integer = e.Location.Y
    Dim dcoX As Integer = DrawCaptureOrigin.X, dcoY As Integer = DrawCaptureOrigin.Y
    If DrawCapture Then
        If curX < dcoX And curY < dcoY Then
            DrawCaptureRectangle = New Rectangle(curX, curY, dcoX - curX, dcoY - curY)
        ElseIf curX < dcoX Then
            DrawCaptureRectangle = New Rectangle(curX, dcoY, dcoX - curX, curY - dcoY)
        ElseIf curY < dcoY Then
            DrawCaptureRectangle = New Rectangle(dcoX, curY, curX - dcoX, dcoY - curY)
        Else
            DrawCaptureRectangle = New Rectangle(dcoX, dcoY, curX - dcoX, curY - dcoY)
        End If
        PictureBox1.Invalidate()
    End If
End Sub

Private Sub PictureBox1_MouseUp(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles PictureBox1.MouseUp
    DrawCapture = False
    PictureBox1.Invalidate()
End Sub

Private Sub PictureBox1_Paint(ByVal sender As Object, ByVal e As System.Windows.Forms.PaintEventArgs) Handles PictureBox1.Paint
    If DrawCaptureRectangle.Width > 0 Then
        e.Graphics.DrawRectangle(Pens.Black, DrawCaptureRectangle)
    End If
End Sub

Answer 1

我无法在我的电脑上重现laggynes，所以我不确定这是否会有所帮助，但请尝试启用Double Buffering。您可以在Form属性中设置它。

Answer 2

MS已经制作了一个名为Win2D的东西，它是

易于使用的Windows Runtime API，可通过GPU加速实现即时模式2D图形渲染。

我刚刚第一次试用了它。以下是性能的粗略比较：PictureBox - 14.5％CPU使用率和CanvasControl - 3.6％（减少4倍;尽管RAM使用率几乎是其中的5倍）。

所以看起来Win2D工作得更快，实际上很容易使用，但有一个问题。您只能将其用于Store App（适用于Windows或Windows Phone）。这意味着它不能在Windows 7上运行。接受或离开它。：）

我有8核CPU，所以我假设100％加载的核心应该显示为12.5％的CPU使用率。

PictureBox CPU usage CanvasControl CPU usage

如何使用Win2D创建相同的应用程序

创建空白商店应用
如果这是您的第一个商店应用，那么您将被要求获得开发者许可;只需点击I Agree。
添加Win2D NuGet包。（在Solution Explorer＆gt; Manage NuGet Packages...）

在MainPage.xaml添加CanvasControl。将其视为PictureBox的替代。

<Page
    x:Class="Win2D_VBNET.MainPage"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:Win2D_VBNET"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    xmlns:canvas="using:Microsoft.Graphics.Canvas.UI.Xaml"
    mc:Ignorable="d">

    <Grid Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">
        <canvas:CanvasControl ClearColor="White"
                              Draw="CanvasControl_Draw"
                              PointerPressed="CanvasControl_PointerPressed"
                              PointerMoved="CanvasControl_PointerMoved"
                              PointerReleased="CanvasControl_PointerReleased"/>
    </Grid>
</Page>

在代码隐藏中添加所有必要的事件处理程序（MainPage.xaml.vb）。代码与您的代码完全相同。

Imports Microsoft.Graphics.Canvas.UI.Xaml
Imports Windows.UI
Imports Microsoft.Graphics.Canvas

Public NotInheritable Class MainPage
    Inherits Page

    Public DrawCapture As Boolean = False
    Public DrawCaptureOrigin As Point
    Public DrawCaptureRectangle As Rect

    Private Sub CanvasControl_PointerPressed(sender As CanvasControl, e As PointerRoutedEventArgs)
        Dim location As Point = e.GetCurrentPoint(Nothing).Position
        DrawCapture = True
        DrawCaptureOrigin = location
        DrawCaptureRectangle = New Rect(location, New Size(1, 1))
    End Sub

    Private Sub CanvasControl_PointerMoved(sender As CanvasControl, e As PointerRoutedEventArgs)
        Dim location As Point = e.GetCurrentPoint(Nothing).Position
        Dim curX As Integer = location.X, curY As Integer = location.Y
        Dim dcoX As Integer = DrawCaptureOrigin.X, dcoY As Integer = DrawCaptureOrigin.Y
        If DrawCapture Then
            If curX < dcoX And curY < dcoY Then
                DrawCaptureRectangle = New Rect(curX, curY, dcoX - curX, dcoY - curY)
            ElseIf curX < dcoX Then
                DrawCaptureRectangle = New Rect(curX, dcoY, dcoX - curX, curY - dcoY)
            ElseIf curY < dcoY Then
                DrawCaptureRectangle = New Rect(dcoX, curY, curX - dcoX, dcoY - curY)
            Else
                DrawCaptureRectangle = New Rect(dcoX, dcoY, curX - dcoX, curY - dcoY)
            End If
        End If
        sender.Invalidate()
    End Sub

    Private Sub CanvasControl_PointerReleased(sender As CanvasControl, e As PointerRoutedEventArgs)
        DrawCapture = False
        sender.Invalidate()
    End Sub

    Private Sub CanvasControl_Draw(sender As CanvasControl, args As CanvasDrawEventArgs)
        If DrawCaptureRectangle.Width > 0 Then
            args.DrawingSession.Antialiasing = CanvasAntialiasing.Aliased
            args.DrawingSession.DrawRectangle(DrawCaptureRectangle, Colors.Black)
        End If
    End Sub

End Class

有没有更快的方法在VB中绘制动态矩形？

2 个答案: