在我们平时做项目的时候，经常会遇到一些需要显示图片的地方，这些图片默认的占位图，
怎么显示才比较合理呢，比如头像，默认图片 可以是名字生成的图片这样比千篇一律的默认图，
显示效果更佳。下边是效果图：
直接上代码：
先说用法
/**
* 根据文字生成drawable
* @param name 显示在图片的名字
* @param fontRes 字体大小
* @param width 图片的宽度
* @param height 图片的高度
* @return
*/
public static TextDrawable getDefaultDrawable(String name, int fontRes, int width, int height) {
String username = name;
if ((name != null && name.length() >= 2)) {
username = name.substring(name.length() - 2, name.length());
} else if (BackwardSupportUtil.isNullOrNil(name)) {
username = "";
}
return TextDrawable.builder()
.beginConfig()
.fontSize(fontRes)
.width(width)
.height(height)
.endConfig()
.buildRound(username, getColorBySeed(BackwardSupportUtil.nullAsNil(username)));
}
说明：主要看一下下边代码的思路，学习东西要先学会它的主要实现思路，理解原理。
首先它是继承了ShapeDrawable ，通过build方法构造出自己想要的图片的属性，
然后再用paint绘制出图形。下边是主要代码
public class TextDrawable extends ShapeDrawable {
private final Paint textPaint;
private final Paint borderPaint;
private static final float SHADE_FACTOR = 0.9f;
private final String text;
private final int color;
private final RectShape shape;
private final int height;
private final int width;
private final int fontSize;
private final float radius;
private final int borderThickness;
private TextDrawable(Builder builder) {
super(builder.shape);
// shape properties
shape = builder.shape;
height = builder.height;
width = builder.width;
radius = builder.radius;
// text and color
text = builder.toUpperCase ? builder.text.toUpperCase() : builder.text;
color = builder.color;
// text paint settings
fontSize = builder.fontSize;
textPaint = new Paint();
textPaint.setColor(builder.textColor);
textPaint.setAntiAlias(true);
textPaint.setFakeBoldText(builder.isBold);
textPaint.setStyle(Paint.Style.FILL);
textPaint.setTypeface(builder.font);
textPaint.setTextAlign(Paint.Align.CENTER);
textPaint.setStrokeWidth(builder.borderThickness);
// border paint settings
borderThickness = builder.borderThickness;
borderPaint = new Paint();
borderPaint.setColor(getDarkerShade(color));
borderPaint.setStyle(Paint.Style.STROKE);
borderPaint.setStrokeWidth(borderThickness);
// drawable paint color
Paint paint = getPaint();
paint.setColor(color);
}
private int getDarkerShade(int color) {
return Color.rgb((int)(SHADE_FACTOR * Color.red(color)),
(int)(SHADE_FACTOR * Color.green(color)),
(int)(SHADE_FACTOR * Color.blue(color)));
}
@Override
public void draw(Canvas canvas) {
super.draw(canvas);
Rect r = getBounds();
// draw border
if (borderThickness > 0) {
drawBorder(canvas);
}
int count = canvas.save();
canvas.translate(r.left, r.top);
// draw text
int width = this.width < 0 ? r.width() : this.width;
int height = this.height < 0 ? r.height() : this.height;
int fontSize = this.fontSize < 0 ? (Math.min(width, height) / 2) : this.fontSize;
textPaint.setTextSize(fontSize);
canvas.drawText(text, width / 2, height / 2 - ((textPaint.descent() + textPaint.ascent()) / 2), textPaint);
canvas.restoreToCount(count);
}
private void drawBorder(Canvas canvas) {
RectF rect = new RectF(getBounds());
rect.inset(borderThickness/2, borderThickness/2);
if (shape instanceof OvalShape) {
canvas.drawOval(rect, borderPaint);
}
else if (shape instanceof RoundRectShape) {
canvas.drawRoundRect(rect, radius, radius, borderPaint);
}
else {
canvas.drawRect(rect, borderPaint);
}
}
@Override
public void setAlpha(int alpha) {
textPaint.setAlpha(alpha);
}
@Override
public void setColorFilter(ColorFilter cf) {
textPaint.setColorFilter(cf);
}
@Override
public int getOpacity() {
return PixelFormat.TRANSLUCENT;
}
@Override
public int getIntrinsicWidth() {
return width;
}
@Override
public int getIntrinsicHeight() {
return height;
}
public static IShapeBuilder builder() {
return new Builder();
}
public static class Builder implements IConfigBuilder, IShapeBuilder, IBuilder {
private String text;
private int color;
private int borderThickness;
private int width;
private int height;
private Typeface font;
private RectShape shape;
public int textColor;
private int fontSize;
private boolean isBold;
private boolean toUpperCase;
public float radius;
private Builder() {
text = "";
color = Color.GRAY;
textColor = Color.WHITE;
borderThickness = 0;
width = -1;
height = -1;
shape = new RectShape();
font = Typeface.create("sans-serif-light", Typeface.NORMAL);
fontSize = -1;
isBold = false;
toUpperCase = false;
}
public IConfigBuilder width(int width) {
this.width = width;
return this;
}
public IConfigBuilder height(int height) {
this.height = height;
return this;
}
public IConfigBuilder textColor(int color) {
this.textColor = color;
return this;
}
public IConfigBuilder withBorder(int thickness) {
this.borderThickness = thickness;
return this;
}
public IConfigBuilder useFont(Typeface font) {
this.font = font;
return this;
}
public IConfigBuilder fontSize(int size) {
this.fontSize = size;
return this;
}
public IConfigBuilder bold() {
this.isBold = true;
return this;
}
public IConfigBuilder toUpperCase() {
this.toUpperCase = true;
return this;
}
@Override
public IConfigBuilder beginConfig() {
return this;
}
@Override
public IShapeBuilder endConfig() {
return this;
}
@Override
public IBuilder rect() {
this.shape = new RectShape();
return this;
}
@Override
public IBuilder round() {
this.shape = new OvalShape();
return this;
}
@Override
public IBuilder roundRect(int radius) {
this.radius = radius;
float[] radii = {radius, radius, radius, radius, radius, radius, radius, radius};
this.shape = new RoundRectShape(radii, null, null);
return this;
}
@Override
public TextDrawable buildRect(String text, int color) {
rect();
return build(text, color);
}
@Override
public TextDrawable buildRoundRect(String text, int color, int radius) {
roundRect(radius);
return build(text, color);
}
@Override
public TextDrawable buildRound(String text, int color) {
round();
return build(text, color);
}
@Override
public TextDrawable build(String text, int color) {
this.color = color;
this.text = text;
return new TextDrawable(this);
}
}
public interface IConfigBuilder {
IConfigBuilder width(int width);
IConfigBuilder height(int height);
IConfigBuilder textColor(int color);
IConfigBuilder withBorder(int thickness);
IConfigBuilder useFont(Typeface font);
IConfigBuilder fontSize(int size);
IConfigBuilder bold();
IConfigBuilder toUpperCase();
IShapeBuilder endConfig();
}
public interface IBuilder {
TextDrawable build(String text, int color);
}
public interface IShapeBuilder {
IConfigBuilder beginConfig();
IBuilder rect();
IBuilder round();
IBuilder roundRect(int radius);
TextDrawable buildRect(String text, int color);
TextDrawable buildRoundRect(String text, int color, int radius);
TextDrawable buildRound(String text, int color);
}
}
