Win2D：CanvasVirtualControl的正確用法

Question

我想繪製從Win2D-Example-Gallery中取得的mandelbrot-set並稍微調整一下。

起初，我有我的所有代碼生成的CanvasAnimatedControl的CreateResources - 方法裏面的天壤之別，但由於性能問題，我又使用着色器（HLSL或PixelShaderEffect）和CanvasVirtualControl做到這一點：

public PixelShaderEffect _effectMandel; 
CanvasVirtualImageSource _sdrc; 

public async Task CreateResources(CanvasVirtualControl sender) 
{ 
    _sdrc = new CanvasVirtualImageSource(sender, new Size(_width, _height)); 
    var arr = await FileHelper.ReadAllBytes("Shaders/Mandelbrot.bin"); 
    if (arr != null) 
    { 
     _effectMandel = new PixelShaderEffect(arr); 

     using (CanvasDrawingSession drawingSession = sender.CreateDrawingSession(new Rect(0,0,_width,_height))) 
     { 
      drawingSession.DrawImage(_effectMandel); 
     } 
    } 
} 

當我運行應用程序，我在使用部分獲得System.Runtime.InteropServices.COMException權利和「App.gics」文件打開了告訴我：

我使用的着色器代碼是這樣的：

// Copyright (c) Microsoft Corporation. All rights reserved. 
// 
// Licensed under the MIT License. See LICENSE.txt in the project root for license information. 


// This shader has no input textures. 
// It generates a mandelbrot fractal. 

#define D2D_INPUT_COUNT 0 
#define D2D_REQUIRES_SCENE_POSITION 

#include "d2d1effecthelpers.hlsli" 


float scale; 
float2 translate; 

static const float4 tapOffsetsX = float4(-0.25, 0.25, -0.25, 0.25); 
static const float4 tapOffsetsY = float4(-0.25, -0.25, 0.25, 0.25); 

static const int iterations = 100; 


D2D_PS_ENTRY(main) 
{ 
    float2 pos = D2DGetScenePosition().xy; 

    // Improve visual quality by supersampling inside the pixel shader, evaluating four separate 
    // versions of the fractal in parallel, each at a slightly different position offset. 
    // The x, y, z, and w components of these float4s contain the four simultaneous computations. 
    float4 c_r = (pos.x + tapOffsetsX) * scale + translate.x; 
    float4 c_i = (pos.y + tapOffsetsY) * scale + translate.y; 

    float4 value_r = 0; 
    float4 value_i = 0; 

    // Evalulate the Mandelbrot fractal. 
    for (int i = 0; i < iterations; i++) 
    { 
     float4 new_r = value_r * value_r - value_i * value_i + c_r; 
     float4 new_i = value_r * value_i * 2 + c_i; 

     value_r = new_r; 
     value_i = new_i; 
    } 

    // Adjust our four parallel results to range 0:1. 
    float4 distanceSquared = value_r * value_r + value_i * value_i; 

    float4 vectorResult = isfinite(distanceSquared) ? saturate(1 - distanceSquared) : 0; 

    // Resolve the supersampling to produce a single scalar result. 
    float result = dot(vectorResult, 0.25); 

    if (result < 1.0/256) 
     return 0; 
    else 
     return float4(result, result, result, 1); 
} 

如果你知道爲什麼發生這種情況，請回答。謝謝！

Answer 1

我需要設置一個計時器以定期使畫布無效並獲得60fps。 我有另外的考慮微軟的例子，最後使用這段代碼的工作了：

DispatcherTimer timer; 
internal void Regions_Invalidated(CanvasVirtualControl sender, CanvasRegionsInvalidatedEventArgs args) 
{ 
    // Configure the Mandelbrot effect to position and scale its output. 
    float baseScale = 0.005f; 
    float scale = (baseScale * 96/sender.Dpi)/(helper._modifiers[1]/1000f); 
    var controlSize = baseScale * sender.Size.ToVector2() * scale; 
    Vector2 translate = (baseScale * sender.Size.ToVector2() * new Vector2(-0.5f,-0f)); 

    _effectMandel.Properties["scale"] = scale; 
    _effectMandel.Properties["translate"] = (Microsoft.Graphics.Canvas.Numerics.Vector2)translate; 
#endif 

    // Draw the effect to whatever regions of the CanvasVirtualControl have been invalidated. 
    foreach (var region in args.InvalidatedRegions) 
    { 
     using (var drawingSession = sender.CreateDrawingSession(region)) 
     { 
      drawingSession.DrawImage(_effectMandel); 
     } 
    } 

    // start timer for fps 
    this.timer = new DispatcherTimer(); 
    int fps = 60; 
    this.timer.Interval = new TimeSpan(0, 0, 0, 0, 100/fps); 
    this.timer.Tick += timer_Tick; 
    this.timer.Start(); 
} 

private void timer_Tick(object sender, object e) 
{ 
    this.timer.Stop(); 
    _canvas.Invalidate(); 
} 

希望這是有幫助的人。