Android 创建一个新的位图并在其中绘制新像素
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Create a new bitmap and draw new pixels into it
提问by Marvos
I'm trying to make an app that will take two pictures you specify via editText, compare the colors of each pixel on both images and create a new picture (bitmap) (that you can save to the sd card) containing the differences between the two original pictures.
我正在尝试制作一个应用程序，它将拍摄您通过 editText 指定的两张图片，比较两个图像上每个像素的颜色并创建一个新图片（位图）（您可以将其保存到 SD 卡）包含两者之间的差异两张原图。
I'm having a problem with creating this new bitmap. How can I achieve my goal? I don't really know how to do this, do I create the new bitmap first and then write into it, or do I get the differences first and then draw a bitmap from that? The pictures will be approx. 300x300 px.
我在创建这个新位图时遇到了问题。我怎样才能实现我的目标？我真的不知道该怎么做，我是先创建新位图然后写入其中，还是先获取差异然后从中绘制位图？图片将是大约。300x300 像素。
回答by Renard
this code is just out of my head and untested but it should get you on the right track.
这段代码只是我的头脑和未经测试，但它应该让你走上正确的轨道。
final int w1 = b1.getWidth();
final int w2 = b2.getWidth();
final int h1 = b1.getHeight();
final int h2 = b2.getHeight();
final int w = Math.max(w1, w2);
final int h = Math.max(h2, h2);
Bitmap compare = Bitmap.createBitmap(w, h, Config.ARGB_8888);
int color1, color2, a, r, g, b;
for (int x = 0; x < w; x++) {
for (int y = 0; y < h; y++) {
if (x < w1 && y < h1) {
color1 = b1.getPixel(x, y);
} else {
color1 = Color.BLACK;
}
if (x < w2 && y < h2) {
color2 = b2.getPixel(x, y);
} else {
color2 = Color.BLACK;
}
a = Math.abs(Color.alpha(color1) - Color.alpha(color2));
r = Math.abs(Color.red(color1) - Color.red(color2));
g = Math.abs(Color.green(color1) - Color.green(color2));
b = Math.abs(Color.blue(color1) - Color.blue(color1));
compare.setPixel(x, y, Color.argb(a, r, g, b));
}
}
b1.recycle();
b2.recycle();
回答by Samuel
I would create the bitmap first and compute the differences between each pixel, but you're welcome to compute the differences first and then use Bitmap.copyPixels, but I think it's easier to understand the first way. Here is an example:
我会先创建位图并计算每个像素之间的差异，但欢迎您先计算差异，然后使用 Bitmap.copyPixels，但我认为第一种方式更容易理解。下面是一个例子：
// Load the two bitmaps
Bitmap input1 = BitmapFactory.decodeFile(/*first input filename*/);
Bitmap input2 = BitmapFactory.decodeFile(/*second input filename*/);
// Create a new bitmap. Note you'll need to handle the case when the two input
// bitmaps are not the same size. For this example I'm assuming both are the
// same size
Bitmap differenceBitmap = Bitmap.createBitmap(input1.getWidth(),
input1.getHeight(), Bitmap.Config.ARGB_8888);
// Iterate through each pixel in the difference bitmap
for(int x = 0; x < /*bitmap width*/; x++)
{
for(int y = 0; y < /*bitmap height*/; y++)
{
int color1 = input1.getPixel(x, y);
int color2 = input2.getPixel(x, y);
int difference = // Compute the difference between pixels here
// Set the color of the pixel in the difference bitmap
differenceBitmap.setPixel(x, y, difference);
}
}
