使用 ColorMatrix 对图片进行风格处理

前言

当我们对图片进行编辑（或者美化）的时候，有一项就是对图片进行风格设置，比如：复古，黑白等，看下面效果图

ColorMatrix

代码

• 界面xml布局

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <ImageView
        android:id="@+id/iv_img"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerHorizontal="true"
        android:layout_margin="25dp"
        android:src="@drawable/ncxy" />

    <Spinner
        android:id="@+id/sp_colorFilter_item"
        android:layout_width="match_parent"
        android:layout_height="45dp"
        android:layout_below="@id/iv_img"
        android:layout_centerHorizontal="true"
        android:layout_marginLeft="45dp"
        android:layout_marginRight="45dp"
        android:entries="@array/colorMatrix"
        android:gravity="center_horizontal" />
</RelativeLayout>

• spinner 监听代码

spinner.setSelection(0, false);
        spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
            @Override
            public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
                imageView.setImageResource(R.drawable.ncxy);
                Bitmap bitmap = ((BitmapDrawable) imageView.getDrawable()).getBitmap();
                switch (position) {
                    case 0:
                        break;
                    case 1:
                        imageView.setImageBitmap(getBitmap(bitmap, getColorMatrixGrayscale()));
                        break;
                    case 2:
                        imageView.setImageBitmap(getBitmap(bitmap, getColorMatrixSepia()));
                        break;
                    case 3:
                        imageView.setImageBitmap(getBitmap(bitmap, getColorMatrixBinary()));
                        break;
                    case 4:
                        imageView.setImageBitmap(getBitmap(bitmap, getColorMatrixInvert()));
                        break;
                    case 5:
                        imageView.setImageBitmap(getBitmap(bitmap, getColorMatrixAlphaBlue()));
                        break;
                    case 6:
                        imageView.setImageBitmap(getBitmap(bitmap, getColorMatrixAlphaPink()));
                        break;
                }
            }

            @Override
            public void onNothingSelected(AdapterView<?> parent) {

            }
        });

第一行是为了解决程序界面打开的时候自动调用监听；在监听里，每选择一个 item，就会调用一个新的方法返回一个 colorMatrix 对象，再通过 getBitmap 方法返回一个新的 bitmap ，设置给 imageview.下面是 getBitmap 方法代码：

/**
     * 根据colorMaxtrix获取对应图片
     *
     * @param colorMatrix
     * @return
     */
    private Bitmap getBitmap(Bitmap original, ColorMatrix colorMatrix) {
        Bitmap bitmap = Bitmap.createBitmap(original.getWidth(), original.getHeight(),
                Bitmap.Config.ARGB_8888);
        Canvas canvas = new Canvas(bitmap);

        Paint paint = new Paint();
        paint.setColorFilter(new ColorMatrixColorFilter(colorMatrix));
        canvas.drawBitmap(original, 0, 0, paint);

        return bitmap;
    }

• 每个 item 对应的方法如下：

 private ColorMatrix getColorMatrixGrayscale() {
        ColorMatrix colorMatrix = new ColorMatrix();
        colorMatrix.setSaturation(0);
        return colorMatrix;
    }

    private ColorMatrix getColorMatrixSepia() {
        ColorMatrix colorMatrix = new ColorMatrix();
        colorMatrix.setSaturation(0);

        ColorMatrix colorScale = new ColorMatrix();
        colorScale.setScale(1, 1, 0.8f, 1);

        // Convert to grayscale, then apply brown color
        colorMatrix.postConcat(colorScale);

        return colorMatrix;
    }

    private ColorMatrix getColorMatrixBinary() {
        ColorMatrix colorMatrix = new ColorMatrix();
        colorMatrix.setSaturation(0);

        float m = 255f;
        float t = -255 * 128f;
        ColorMatrix threshold = new ColorMatrix(new float[]{
                m, 0, 0, 1, t,
                0, m, 0, 1, t,
                0, 0, m, 1, t,
                0, 0, 0, 1, 0
        });

        // Convert to grayscale, then scale and clamp
        colorMatrix.postConcat(threshold);

        return colorMatrix;
    }

    private ColorMatrix getColorMatrixInvert() {
        return new ColorMatrix(new float[]{
                -1, 0, 0, 0, 255,
                0, -1, 0, 0, 255,
                0, 0, -1, 0, 255,
                0, 0, 0, 1, 0
        });
    }

    private ColorMatrix getColorMatrixAlphaBlue() {
        return new ColorMatrix(new float[]{
                0, 0, 0, 0, 0,
                0.3f, 0, 0, 0, 50,
                0, 0, 0, 0, 255,
                0.2f, 0.4f, 0.4f, 0, -30
        });
    }

    private ColorMatrix getColorMatrixAlphaPink() {
        return new ColorMatrix(new float[]{
                0, 0, 0, 0, 255,
                0, 0, 0, 0, 0,
                0.2f, 0, 0, 0, 50,
                0.2f, 0.2f, 0.2f, 0, -20
        });
    }

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以上就是完整代码.