透明的自适应图标背景 [英] Transparent adaptive icon background

问题描述

所以我已经在这个应用程序上工作了几个星期，并且我开始构建图标.我有Android Studio 3.0.1，并且它们似乎已经改变了制作图像资产的方式，现在它们具有自适应图标了.我为我的应用制作了一个带有透明背景的图标.在此之前，我只是将形状更改为"none"，并且不会生成任何背景.但是，除非我没有用遗产"，否则现在这不是一个选择.背景颜色似乎不支持透明性.即使在 ic_launcher.xml 中，我将背景设置为透明颜色，但图标仍显示为黑色背景.

So I have been working on this app for a couple weeks and I started to build the icon. I have Android Studio 3.0.1 and they seem to have changed the way Image Assets are made, now they have adaptive icons. I made an icon with transparent background for my app. Before, I would just change the shape to "none" and there would be no background generated. But now that is not an option unless I go to "legacy" which is useless. The background color does not seem to support transparency. Even if in the ic_launcher.xml I set the background to a transparent color but the icon still appears with a black background.

这是我的 ic_lancher.xml

<?xml version="1.0" encoding="utf-8"?>
<adaptive-icon xmlns:android="http://schemas.android.com/apk/res/android">
    <background android:drawable="@color/transparent"/>
    <foreground android:drawable="@mipmap/ic_launcher_foreground"/>
</adaptive-icon>

和ic_launcher_round.xml相同. @ color/transparent 位是this:

And ic_launcher_round.xml is the same. The @color/transparent bit is a this:

<color name="transparent">#00000000</color>

推荐答案

TL; DR 自适应图标不能具有透明背景

TL;DR Adaptive Icons cannot have transparent Background

根据Android 8.0框架的源代码，< background> 层本质上是不透明的；如问题中所述，框架用不透明的黑色填充背景.

According to the source code of Android 8.0 framework, the <background> layer is inherently opaque; the framework fills the background with opaque black, as mentioned in the question.

该框架有一个 AdaptiveIconDrawable 类，该类绘制了自适应启动器图标. https://developer.android.com/reference/android/graphics/drawable/AdaptiveIconDrawable.html
元素< adaptive-icon> 创建它的一个实例:

The framework has a class AdaptiveIconDrawable, which draws adaptive launcher icons. https://developer.android.com/reference/android/graphics/drawable/AdaptiveIconDrawable.html
The element <adaptive-icon> creates an instance of it:

除了动态创建之外，还可以使用< adaptive-icon> 标签通过XML填充来创建此类.

This class can also be created via XML inflation using <adaptive-icon> tag in addition to dynamic creation.

The source code of method draw in AdaptiveIconDrawable.java is:

@Override
public void draw(Canvas canvas) {
    if (mLayersBitmap == null) {
        return;
    }
    if (mLayersShader == null) {
        mCanvas.setBitmap(mLayersBitmap);
        mCanvas.drawColor(Color.BLACK);
        for (int i = 0; i < mLayerState.N_CHILDREN; i++) {
            if (mLayerState.mChildren[i] == null) {
                continue;
            }
            final Drawable dr = mLayerState.mChildren[i].mDrawable;
            if (dr != null) {
                dr.draw(mCanvas);
            }
        }
        mLayersShader = new BitmapShader(mLayersBitmap, TileMode.CLAMP, TileMode.CLAMP);
        mPaint.setShader(mLayersShader);
    }
    if (mMaskBitmap != null) {
        Rect bounds = getBounds();
        canvas.drawBitmap(mMaskBitmap, bounds.left, bounds.top, mPaint);
    }
}

简而言之， Canvas 实例会收到要绘制的位图，最初它用黑色填充位图.然后前景可绘制对象和背景可绘制对象完成这项工作:

In short, a Canvas instance receives a bitmap to draw into, and initially it fills the bitmap with black color. Then the foreground drawable and the background drawable do the job:

mCanvas.setBitmap(mLayersBitmap); // reset
mCanvas.drawColor(Color.BLACK);   // fill
for (int i = 0; i < mLayerState.N_CHILDREN; i++) { // two layers
    ...
    final Drawable dr = mLayerState.mChildren[i].mDrawable;
    ...
        dr.draw(mCanvas); // draw
    ...
}

Color.BLACK 是不透明的:

0xff000000

0xff000000

方法 drawColor 填充位图使用 SRC_OVER 模式:

The method drawColor fills the bitmap with it, using SRC_OVER mode:

使用srcover porterduff模式以指定的颜色填充整个画布的位图(仅限于当前剪辑).

Fill the entire canvas' bitmap (restricted to the current clip) with the specified color, using srcover porterduff mode.

因此，即使您为背景设置了透明的颜色，背景也始终是不透明的，如下面的屏幕截图所示(来自我的答案(类似问题).

So, the background will be always opaque, even if you set transparent color to the background, as in the screenshot below (from my answer to a similar question).

这篇关于透明的自适应图标背景的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！