如何将图像（位图）调整为给定大小？ [重复]

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How to Resize a Bitmap in Android? 13 answers
如何调整Android中的位图大小？ 13个答案

How to resize image (Bitmap) to for example 800*480 programatically ? I have retrieved a picture in my app which is ~1MB and I need to scale it down to 800*480 I have loaded that picture and compressed it but how do I do to make it smaller :

如何以编程方式将图像（位图）调整为800 * 480？我已经在我的应用程序中检索到了大约1MB的图片，我需要将其缩小到800 * 480我已经加载了该图片并对其进行了压缩但是我该如何缩小它：

ByteArrayOutputStream bos = new ByteArrayOutputStream(8192);
photo.compress(CompressFormat.JPEG, 25, bos);

5 个解决方案

#1

Bitmap scaledBitmap = scaleDown(realImage, MAX_IMAGE_SIZE, true);

Scale down method:

缩小方法：

public static Bitmap scaleDown(Bitmap realImage, float maxImageSize,
        boolean filter) {
    float ratio = Math.min(
            (float) maxImageSize / realImage.getWidth(),
            (float) maxImageSize / realImage.getHeight());
    int width = Math.round((float) ratio * realImage.getWidth());
    int height = Math.round((float) ratio * realImage.getHeight());

    Bitmap newBitmap = Bitmap.createScaledBitmap(realImage, width,
            height, filter);
    return newBitmap;
}

#2

 Bitmap yourBitmap;
 Bitmap resized = Bitmap.createScaledBitmap(yourBitmap, newWidth, newHeight, true);

or:

要么：

 resized = Bitmap.createScaledBitmap(yourBitmap,(int)(yourBitmap.getWidth()*0.8), (int)(yourBitmap.getHeight()*0.8), true);

#3

You can scale bitmaps by using canvas.drawBitmap with providing matrix, for example:

您可以使用canvas.drawBitmap并提供矩阵来缩放位图，例如：

public static Bitmap scaleBitmap(Bitmap bitmap, int wantedWidth, int wantedHeight) {
        Bitmap output = Bitmap.createBitmap(wantedWidth, wantedHeight, Config.ARGB_8888);
        Canvas canvas = new Canvas(output);
        Matrix m = new Matrix();
        m.setScale((float) wantedWidth / bitmap.getWidth(), (float) wantedHeight / bitmap.getHeight());
        canvas.drawBitmap(bitmap, m, new Paint());

        return output;
    }

#4

The other answers are correct as to "how" to resize them, but I would also thrown in the recommendation to just grab the resolution you are interested in, to begin with. Most Android devices offer a range of resolutions and you should pick one that gives you a file size that you're comfortable with. The biggest reason for this is that the native Android scaling algorithm (as detailed by Jin35 and Padma Kumar) produces pretty crappy results. It's not going to give you Photoshop quality resizing, even downscaling (to say nothing of upscaling, which I know you're not asking about, but that's just a non-starter).

其他答案对于如何调整它们的大小是正确的，但我也会在建议中抛出你感兴趣的分辨率，开头。大多数Android设备提供一系列分辨率，您应该选择一个能够提供您感觉舒适的文件大小的设备。最大的原因是原生的Android缩放算法（由Jin35和Padma Kumar详细说明）会产生非常糟糕的结果。它不会给你Photoshop质量大小调整，甚至缩小尺寸（更不用说升级了，我知道你没有问过，但这只是一个非首发）。

So, you should try their solution and if you're happy with the outcome, great. But if not, I'd write a function that offers a range of width that you're happy with, and looks for that dimension (or whatever's closest) in the device's available picture size array and just set it and use it.

所以，你应该尝试他们的解决方案，如果你对结果感到满意，那很好。但如果没有，我会编写一个功能，提供您满意的宽度范围，并在设备的可用图片大小数组中查找该尺寸（或最接近的尺寸）并设置并使用它。

#5

In MonoDroid here's how (c#)

在MonoDroid这里是如何（c＃）

/// <summary>
/// Graphics support for resizing images
/// </summary>
public static class Graphics
{
    public static Bitmap ScaleDownBitmap(Bitmap originalImage, float maxImageSize, bool filter)
    {
        float ratio = Math.Min((float)maxImageSize / originalImage.Width, (float)maxImageSize / originalImage.Height);
        int width = (int)Math.Round(ratio * (float)originalImage.Width);
        int height =(int) Math.Round(ratio * (float)originalImage.Height);

        Bitmap newBitmap = Bitmap.CreateScaledBitmap(originalImage, width, height, filter);
        return newBitmap;
    }

    public static Bitmap ScaleBitmap(Bitmap originalImage, int wantedWidth, int wantedHeight)
    {
        Bitmap output = Bitmap.CreateBitmap(wantedWidth, wantedHeight, Bitmap.Config.Argb8888);
        Canvas canvas = new Canvas(output);
        Matrix m = new Matrix();
        m.SetScale((float)wantedWidth / originalImage.Width, (float)wantedHeight / originalImage.Height);
        canvas.DrawBitmap(originalImage, m, new Paint());
        return output;
    }

}

#1

Bitmap scaledBitmap = scaleDown(realImage, MAX_IMAGE_SIZE, true);