无法在此while循环中设置正确的值 [英] Can't set the correct value in this while loop
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问题描述
我已将此代码翻译成VB.NET，这是一个检查图像是否为灰度的函数。
I have translated this code to VB.NET which is a function to check if a image is grayscale.
private static unsafe bool IsGrayScale(Image image)
{
using (var bmp = new Bitmap(image.Width, image.Height, PixelFormat.Format32bppArgb))
{
using (var g = Graphics.FromImage(bmp))
{
g.DrawImage(image, 0, 0);
}
var data = bmp.LockBits(new Rectangle(0, 0, bmp.Width, bmp.Height), ImageLockMode.ReadOnly, bmp.PixelFormat);
var pt = (int*)data.Scan0;
var res = true;
for (var i = 0; i < data.Height * data.Width; i++)
{
var color = Color.FromArgb(pt[i]);
if (color.A != 0 && (color.R != color.G || color.G != color.B))
{
res = false;
break;
}
}
bmp.UnlockBits(data);
return res;
}
}
C＃代码正在工作，需要我做一个小修改尝试做一个功能，检查一个图像是否有一定的RGB颜色，但最重要的部分是不工作：
The C# code is working but is not doing what I need so I did a little modifications trying to make a function which checks if a image has certain RGB color but the most important part is not working:
Dim color__1 = Color.FromArgb(pt(i))
例外：
Error 1 Expression is not an array or a method, and cannot have an argument list. C:\Visual Studio Projects\WindowsApplication9\WindowsApplication9\Form1.vb 21 47 WindowsApplication9
以下是已翻译的代码：
Imports System.Drawing.Imaging
Public Class Form1
Private Shared Function ImageHasColor(ByVal image As Image, ByVal R As Int32, ByVal G As Int32, ByVal B As Int32) As Boolean
Using bmp = New Bitmap(image.Width, image.Height, PixelFormat.Format32bppArgb)
Using graph = Graphics.FromImage(bmp)
graph.DrawImage(image, 0, 0)
End Using
Dim data = bmp.LockBits(New Rectangle(0, 0, bmp.Width, bmp.Height), ImageLockMode.[ReadOnly], bmp.PixelFormat)
Dim pt = CType(data.Scan0, Integer)
MsgBox(pt)
Dim res As Boolean
Dim i = 0
While i < data.Height * data.Width
Dim color__1 = Color.FromArgb(pt(i))
If color__1.A <> 0 AndAlso color__1.R = R AndAlso color__1.G = G AndAlso color__1.B = B Then
res = True
Exit While
End If
System.Math.Max(System.Threading.Interlocked.Increment(i), i - 1)
End While
bmp.UnlockBits(data)
Return res
End Using
End Function
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
Dim bmp = New Bitmap("C:\Users\Administrador\Desktop\PrtScr capture_3.jpg")
MsgBox(ImageHasColor(bmp, 240, 240, 240))
End Sub
End Class
UPDATE：
UPDATE:
这些代码只适用于第一次，如果我多次使用它，我会得到这个错误：
Those codes works only for the first time, if I use it more than one time I get this error:
strong>尝试读取或写入受保护的内存
Attempted to read or write protected memory
1。
Private Shared Function ImageHasColor(ByVal image As Image, ByVal R As Int32, ByVal G As Int32, ByVal B As Int32) As Boolean
Using bmp = New Bitmap(image.Width, image.Height, PixelFormat.Format32bppArgb)
Using graph = Graphics.FromImage(bmp)
graph.DrawImage(image, 0, 0)
End Using
Dim color__1 As Color
Dim byt
Dim data = bmp.LockBits(New Rectangle(0, 0, bmp.Width, bmp.Height), ImageLockMode.[ReadOnly], bmp.PixelFormat)
Dim pt = CType(data.Scan0, Integer)
Dim res As Boolean
For i = 0 To data.Height * data.Width - 1
color__1 = Color.FromArgb(Marshal.ReadInt32(pt, i * 4))
If color__1.A <> 0 AndAlso color__1.R = R AndAlso color__1.G = G AndAlso color__1.B = B Then
res = True
Exit For
End If
'System.Math.Max(System.Threading.Interlocked.Increment(i), i - 1)
Next
bmp.UnlockBits(data)
Return res
End Using
End Function
2。
Private Shared Function ImageHasColor(ByVal image As Image, ByVal R As Int32, ByVal G As Int32, ByVal B As Int32) As Boolean
Using bmp = New Bitmap(image.Width, image.Height, PixelFormat.Format32bppArgb)
Using graph = Graphics.FromImage(bmp)
graph.DrawImage(image, 0, 0)
End Using
Dim color__1 As Color
Dim byt
Dim data = bmp.LockBits(New Rectangle(0, 0, bmp.Width, bmp.Height), ImageLockMode.[ReadOnly], bmp.PixelFormat)
Dim pt = CType(data.Scan0, Integer)
Dim res As Boolean
Dim i = 0
While i < data.Height * data.Width
color__1 = Color.FromArgb(Marshal.ReadInt32(pt, i * 4))
If color__1.A <> 0 AndAlso color__1.R = R AndAlso color__1.G = G AndAlso color__1.B = B Then
res = True
Exit While
End If
System.Math.Max(System.Threading.Interlocked.Increment(i), i - 1)
End While
bmp.UnlockBits(data)
Return res
End Using
End Function
UPDATE： p>
UPDATE:
此代码似乎有效
Private Shared Function ImageHasColor(ByVal image As Image, ByVal R As Int32, ByVal G As Int32, ByVal B As Int32) As Boolean
Try
Using bmp = New Bitmap(image.Width, image.Height, PixelFormat.Format32bppArgb)
Using graph = Graphics.FromImage(bmp) : graph.DrawImage(image, 0, 0) : End Using
Dim Pixel_Color As Color
Dim Ditmap_Data = bmp.LockBits(New Rectangle(0, 0, bmp.Width, bmp.Height), ImageLockMode.[ReadOnly], bmp.PixelFormat)
Dim pt As IntPtr = CType(Ditmap_Data.Scan0, IntPtr)
For i = 0 To Ditmap_Data.Height * Ditmap_Data.Width - 1
Pixel_Color = Color.FromArgb(Marshal.ReadInt32(pt, i * 4))
If Pixel_Color.A <> 0 AndAlso Pixel_Color.R = R AndAlso Pixel_Color.G = G AndAlso Pixel_Color.B = B Then
bmp.UnlockBits(Ditmap_Data)
Return True
End If
Next
bmp.UnlockBits(Ditmap_Data)
Return False
End Using
Catch ex As Exception
MsgBox(ex.Message)
Return Nothing
End Try
End Function
推荐答案
现在你只是反了。为什么这些UnlockBits在循环中？你在原始代码中看到它们吗？
Now you're just being contrarian. Why these UnlockBits in the loop? Do you see them in the original code? Remove them at once.
Private Shared Function HasColor(ByVal image As Image, ByVal toFind As Color) As Boolean
Using bmp = New Bitmap(image.Width, image.Height, PixelFormat.Format32bppArgb)
Using graph = Graphics.FromImage(bmp)
graph.DrawImage(image, 0, 0)
End Using
Dim data = bmp.LockBits(New Rectangle(0, 0, bmp.Width, bmp.Height), ImageLockMode.[ReadOnly], bmp.PixelFormat)
Dim pt = data.Scan0 'Since we can't use a pointer in VB.Net, we'll stick to IntPtr for now
Dim res As Boolean = False
For i=0 To data.Height * data.Width - 1
Dim foundColor as Int32 = Marshal.ReadInt32(pt, i*4)
If (foundColor and &HFF000000) <> 0 AndAlso ( (foundColor and &H00FFFFFF) = (toFind.ToArgb() and &H00FFFFFF) ) Then
res = True
Exit For
End If
Next
bmp.UnlockBits(data)
Return res
End Using
End Function
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
Dim bmp = New Bitmap("C:\Users\Administrador\Desktop\PrtScr capture_3.jpg")
MsgBox(ImageHasColor(bmp, Color.FromArgb(240, 240, 240)))
End Sub
结束类
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