DrawImage 无法正确定位切片图像

Question

几天来，我一直试图找出为什么我的九片代码不能按预期工作。据我所知， Graphics.DrawImage 方法似乎存在问题，它错误地处理了我的九个切片图像。所以我的问题是如何补偿在紧凑框架上运行代码时执行的不正确的缩放。我可能会补充一点，当在完整的框架环境中运行时，这段代码当然可以完美运行。仅当将图像缩放为较大图像时才会出现此问题，反之则不然。这是片段：

public class NineSliceBitmapSnippet
{
    private Bitmap m_OriginalBitmap;

    public int CornerLength { get; set; }

    /// <summary>
    /// Initializes a new instance of the NineSliceBitmapSnippet class.
    /// </summary>
    public NineSliceBitmapSnippet(Bitmap bitmap)
    {
        CornerLength = 5;
        m_OriginalBitmap = bitmap;
    }

    public Bitmap ScaleSingleBitmap(Size size)
    {
        Bitmap scaledBitmap = new Bitmap(size.Width, size.Height);
        int[] horizontalTargetSlices = Slice(size.Width);
        int[] verticalTargetSlices = Slice(size.Height);

        int[] horizontalSourceSlices = Slice(m_OriginalBitmap.Width);
        int[] verticalSourceSlices = Slice(m_OriginalBitmap.Height);

        using (Graphics graphics = Graphics.FromImage(scaledBitmap))
        {
            using (Brush brush = new SolidBrush(Color.Fuchsia))
            {
                graphics.FillRectangle(brush, new Rectangle(0, 0, size.Width, size.Height));
            }

            int horizontalTargetOffset = 0;
            int verticalTargetOffset = 0;

            int horizontalSourceOffset = 0;
            int verticalSourceOffset = 0;

            for (int x = 0; x < horizontalTargetSlices.Length; x++)
            {
                verticalTargetOffset = 0;
                verticalSourceOffset = 0;
                for (int y = 0; y < verticalTargetSlices.Length; y++)
                {
                    Rectangle destination = new Rectangle(horizontalTargetOffset, verticalTargetOffset, horizontalTargetSlices[x], verticalTargetSlices[y]);
                    Rectangle source = new Rectangle(horizontalSourceOffset, verticalSourceOffset, horizontalSourceSlices[x], verticalSourceSlices[y]);

                    graphics.DrawImage(m_OriginalBitmap, destination, source, GraphicsUnit.Pixel);

                    verticalTargetOffset += verticalTargetSlices[y];
                    verticalSourceOffset += verticalSourceSlices[y];
                }

                horizontalTargetOffset += horizontalTargetSlices[x];
                horizontalSourceOffset += horizontalSourceSlices[x];
            }
        }
        return scaledBitmap;
    }

    public int[] Slice(int length)
    {
        int cornerLength = CornerLength;

        if (length <= (cornerLength * 2))
            throw new Exception("Image to small for sliceing up");

        int[] slices = new int[3];
        slices[0] = cornerLength;
        slices[1] = length - (2 * cornerLength);
        slices[2] = cornerLength;

        return slices;
    }
}

所以，我的问题是，现在有人可以如何补偿不正确的缩放吗？

/担

Answer 1

经过更多的尝试和错误，我终于找到了解决我的问题的方法。缩放问题始终存在于顶部中心、右侧中心、底部中心和左侧中心切片，因为根据九切片缩放的逻辑，它们总是仅在一个方向上拉伸。如果我在应用正确的拉伸之前对这些切片应用临时的方形拉伸，则最终的位图将是正确的。同样，该问题仅在 Windows CE 设备（智能设备）的 .Net Compact Framework 中可见。这是针对 CF 中的错误进行调整的代码片段。我现在唯一担心的是，由于校正代码，方形拉伸的切片将占用更多内存。另一方面，这一步的时间很短，所以我可能会侥幸逃脱。 ;)

    public class NineSliceBitmapSnippet
{
    private Bitmap m_OriginalBitmap;

    public int CornerLength { get; set; }

    public NineSliceBitmapSnippet(Bitmap bitmap)
    {
        CornerLength = 5;
        m_OriginalBitmap = bitmap;
    }

    public Bitmap Scale(Size size)
    {
        if (m_OriginalBitmap != null)
        {
            return ScaleSingleBitmap(size);
        }

        return null;
    }

    public Bitmap ScaleSingleBitmap(Size size)
    {
        Bitmap scaledBitmap = new Bitmap(size.Width, size.Height);
        int[] horizontalTargetSlices = Slice(size.Width);
        int[] verticalTargetSlices = Slice(size.Height);

        int[] horizontalSourceSlices = Slice(m_OriginalBitmap.Width);
        int[] verticalSourceSlices = Slice(m_OriginalBitmap.Height);

        using (Graphics graphics = Graphics.FromImage(scaledBitmap))
        {
            using (Brush brush = new SolidBrush(Color.Fuchsia))
            {
                graphics.FillRectangle(brush, new Rectangle(0, 0, size.Width, size.Height));
            }

            int horizontalTargetOffset = 0;
            int verticalTargetOffset = 0;

            int horizontalSourceOffset = 0;
            int verticalSourceOffset = 0;

            for (int x = 0; x < horizontalTargetSlices.Length; x++)
            {
                verticalTargetOffset = 0;
                verticalSourceOffset = 0;
                for (int y = 0; y < verticalTargetSlices.Length; y++)
                {
                    Rectangle destination = new Rectangle(horizontalTargetOffset, verticalTargetOffset, horizontalTargetSlices[x], verticalTargetSlices[y]);
                    Rectangle source = new Rectangle(horizontalSourceOffset, verticalSourceOffset, horizontalSourceSlices[x], verticalSourceSlices[y]);

                    bool isWidthAffectedByVerticalStretch = (y == 1 && (x == 0 || x == 2) && destination.Height > source.Height);
                    bool isHeightAffectedByHorizontalStretch = (x == 1 && (y == 0 || y == 2) && destination.Width > source.Width);
                    if (isHeightAffectedByHorizontalStretch)
                    {
                        BypassDrawImageError(graphics, destination, source, Orientation.Horizontal);
                    }
                    else if (isWidthAffectedByVerticalStretch)
                    {
                        BypassDrawImageError(graphics, destination, source, Orientation.Vertical);
                    }
                    else
                    {
                        graphics.DrawImage(m_OriginalBitmap, destination, source, GraphicsUnit.Pixel);
                    }

                    verticalTargetOffset += verticalTargetSlices[y];
                    verticalSourceOffset += verticalSourceSlices[y];
                }

                horizontalTargetOffset += horizontalTargetSlices[x];
                horizontalSourceOffset += horizontalSourceSlices[x];
            }
        }
        return scaledBitmap;
    }

    private void BypassDrawImageError(Graphics graphics, Rectangle destination, Rectangle source, Orientation orientationAdjustment)
    {
        Size adjustedSize = Size.Empty;
        switch (orientationAdjustment)
        {
            case Orientation.Horizontal:
                adjustedSize = new Size(destination.Width, destination.Width);
                break;
            case Orientation.Vertical:
                adjustedSize = new Size(destination.Height, destination.Height);
                break;
            default:
                break;
        }

        using (Bitmap quadScaledBitmap = new Bitmap(adjustedSize.Width, adjustedSize.Height))
        {
            using (Graphics tempGraphics = Graphics.FromImage(quadScaledBitmap))
            {
                tempGraphics.Clear(Color.Fuchsia);
                tempGraphics.DrawImage(m_OriginalBitmap, new Rectangle(0, 0, adjustedSize.Width, adjustedSize.Height), source, GraphicsUnit.Pixel);
            }
            graphics.DrawImage(quadScaledBitmap, destination, new Rectangle(0, 0, quadScaledBitmap.Width, quadScaledBitmap.Height), GraphicsUnit.Pixel);
        }
    }

    public int[] Slice(int length)
    {
        int cornerLength = CornerLength;

        if (length <= (cornerLength * 2))
            throw new Exception("Image to small for sliceing up");

        int[] slices = new int[3];
        slices[0] = cornerLength;
        slices[1] = length - (2 * cornerLength);
        slices[2] = cornerLength;

        return slices;
    }
}