Android(安卓)TextView中显示彩虹字

一. 實現很簡單，就是對顏色進行線性的漸變。用到的類是LinearGradient.直接貼代碼：

public class Test extends Activity { private TextViewTest mTextViewTest; /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) {  super.onCreate(savedInstanceState);  mTextViewTest = new TextViewTest(this);  setContentView(mTextViewTest); } public class TextViewTest extends TextView {  private LinearGradient mGradient;  private int[] mGradientColors = { Color.RED, Color.rgb(255, 165, 0),    Color.YELLOW, Color.GREEN, Color.rgb(0, 255, 255), Color.BLUE,    Color.rgb(160, 32, 240) };  private int mTitleWidth;  private String mTitle = "三十六天罡,七十二地煞,乃是天地正邪之氣所生,如今奉命下凡轉世為科學家.但法用以正,則可以造福人群;";  public TextViewTest(Context context) {   super(context);   // TODO Auto-generated constructor stub   setLayoutParams(new LinearLayout.LayoutParams(     LinearLayout.LayoutParams.FILL_PARENT,     LinearLayout.LayoutParams.FILL_PARENT));   setWillNotDraw(false);  }  @Override  protected void onDraw(Canvas canvas) {   // TODO Auto-generated method stub   super.onDraw(canvas);   measure(0, 0);      Paint paint = new Paint();   paint.setStyle(Style.FILL_AND_STROKE);   mGradient = new LinearGradient(0, 0, getWidth(),     getMeasuredHeight(), mGradientColors, null, TileMode.REPEAT);   paint.setShader(mGradient);      mTitleWidth = 0;   float[] width = new float[mTitle.length()];   paint.getTextWidths(mTitle, width);   Log.i("Tag", "Width.length= " + width.length);   int start = 0;   int offsetY = 10;   for (int j = 0; j < mTitle.length(); j++) {    mTitleWidth += (int) Math.ceil(width[j]);    if (mTitleWidth > getWidth()) {     canvas.drawText(mTitle.substring(start, j), 0, offsetY,       paint);     mTitleWidth = 0;     start = start + j;     offsetY = offsetY + getMeasuredHeight() + 5;     j--;    }   }   if (mTitleWidth > 0) {    canvas.drawText(mTitle.substring(start), 0, offsetY, paint);   }  } }}

二. 實例圖

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