JavaMe開發(fā)：低級界面繪圖之點陣字
【問題描述】JavaMe自帶的字體只有三種：Font.SIZE_SMALL、Font.SIZE_MEDIA和Font.SIZE_LARGE，所謂的Font.SIZE_LARGE其實也不是很大。如果要繪制其他字號的字體該怎么辦呢？運用低級界面Canvas繪制的點陣字是一個不錯的選擇。
【字模工具】
曉奇工作室
取模方式：從左到右從上到下，橫向8點左高位
【分析】
所謂“點陣字”就是文字是由點陣構(gòu)成的。點陣字有兩個基本屬性，那就是寬(width)和高(height)。先看一個例子：
如圖1所示，Asc5x8表示寬度為5，高度為8的點陣字集。一個char型的字符能表示8位。取模工具實際上是用二進(jìn)制“1”，表示點陣的文字。用二進(jìn)制的“0”，表示非文字的空白塊。以Asc5x8的“！”為例進(jìn)行講解：
0x20,0x20,0x20,0x20,0x20,0x00,0x20,0x00, // -!-
對應(yīng)的點陣為：
00100000
00100000
00100000
00100000
00100000
00000000
00100000
00000000
注意到，如果將“1”替換為像素點顯示，而“0”替換為空白塊。則剛好顯示為一個“！”號。寬度為5，所以用一個字節(jié)表示就可以了。如果寬度超過一個字節(jié)，那么如何計算需要多少個字節(jié)才能表示寬度呢？原則是，寬度的表示必須為字節(jié)的倍數(shù)。如寬度為9，那么超過一個字節(jié)，所以用2個字節(jié)表示。
總結(jié)寬度所需字節(jié)計算公式如下：
n = (width-1)/8+1
Asc5x8中width即為5.
那么高度如何計算呢？高度其實不用進(jìn)行計算，由取模軟件完成了。
明白上述原理后，就很簡單了。且看代碼。
【代碼清單】
- package com.token.view.components;
- import javax.microedition.lcdui.Graphics;
- import javax.microedition.lcdui.game.GameCanvas;
- public class CustomFont {
- public final char font24x48[][] = // ASCII
- {
- {
- 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, // - -
- 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
- 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
- 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
- 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
- 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
- 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
- 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
- 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
- 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
- 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
- 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
- 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
- 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
- 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
- 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
- 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
- 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00
- },
- {
- 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, // -!-
- 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
- 0x00,0x00,0x00,0x00,0x00,0x00,0x30,0x00,
- 0x00,0x78,0x00,0x00,0x78,0x00,0x00,0x78,
- 0x00,0x00,0x78,0x00,0x00,0x78,0x00,0x00,
- 0x78,0x00,0x00,0x78,0x00,0x00,0x78,0x00,
- 0x00,0x78,0x00,0x00,0x78,0x00,0x00,0x30,
- 0x00,0x00,0x30,0x00,0x00,0x30,0x00,0x00,
- 0x30,0x00,0x00,0x30,0x00,0x00,0x30,0x00,
- 0x00,0x30,0x00,0x00,0x30,0x00,0x00,0x30,
- 0x00,0x00,0x30,0x00,0x00,0x30,0x00,0x00,
- 0x30,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
- 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
- 0x00,0x00,0x70,0x00,0x00,0xF8,0x00,0x00,
- 0xF8,0x00,0x00,0xF8,0x00,0x00,0x70,0x00,
- 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
- 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
- 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00
- },
- {
- 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, // -"-
- 0x00,0x00,0xC0,0xC0,0x01,0xE1,0xE0,0x03,
- 0xE3,0xE0,0x03,0xC3,0xC0,0x07,0x87,0x80,
- 0x07,0x07,0x00,0x0E,0x0E,0x00,0x0C,0x0C,
- 0x00,0x18,0x18,0x00,0x10,0x10,0x00,0x20,
- 0x20,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
- 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
- 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
- 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
- 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
- 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
- 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
- 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
- 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
- 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
- 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
- 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
- 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00
- },
- ...
- {
- 0x07,0x80,0x00,0x1F,0xC0,0x00,0x10,0xE0, // --
- 0x04,0x20,0x70,0x04,0x20,0x38,0x08,0x40,
- 0x1C,0x08,0x40,0x0F,0x10,0x00,0x07,0xF0,
- 0x00,0x03,0xC0,0x00,0x00,0x00,0x00,0x00,
- 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
- 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
- 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
- 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
- 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
- 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
- 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
- 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
- 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
- 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
- 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
- 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
- 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
- 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00
- }
- };
- public CustomFont()
- {
- }
- public void drawmat(GameCanvas canvas, Graphics g, char mat[], int w, int h, int x, int y, int color)
- {
- int i,j,k,n;
- n = (w-1)/8+1;
- for(j=0; j<h; j++)
- {
- for(i=0; i<n; i++)
- {
- for(k=0; k<8; k++)
- {
- if (!((mat[j * n + i] & (0x80 >> k)) == 0)) /* 測試為1的位則顯示 */
- {
- g.setColor(color);
- g.drawLine(x + i * 8 + k, y + j, x + i * 8 + k, y + j);
- }
- }
- }
- }
- }
- }
n就是表示整個寬度需要的字節(jié)數(shù)，由于寬度為24，故需要3個字節(jié)表示。j記錄縱向（高度）位置。代碼的處理，就是通過一個畫線函數(shù)進(jìn)行的。每次以字節(jié)為單位(變量k處理)，對“1”進(jìn)行檢測，檢測到1后，記錄k的位置。
【調(diào)用方法】
CustomFont主要用于GameCanvas派生的類。在繼承GameCanvas的類中：
(1)聲明對象
- private CustomFont cf;
(2) 初始化對象(在構(gòu)造函數(shù)中)
- cf = new CustomFont();
(3) 調(diào)用方法(畫字符串passwd)
- for(int i=0; i<passwd.length(); i++)
- {
- cf.drawmat(this, graphics, cf.font24x48[passwd.charAt(i)-' '], 24, 48, (width-6*24)/2+i*24, (height-48)/3, Color.WHITE);
- }
【效果】
圖2中，框中的文字就是通過繪制得到的。
【設(shè)計參考】
(1) http://aiquantong.iteye.com/blog/1457906
(2) http://blog.csdn.net/alleniversoncomputer/article/details/7016368
原文鏈接：http://blog.csdn.net/tandesir/article/details/7506065
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