JavaMe開發中低級界面繪圖怎么進行點陣字

JavaMe開發中低級界面繪圖怎么進行點陣字，很多新手對此不是很清楚，為了幫助大家解決這個難題，下面小編將為大家詳細講解，有這方面需求的人可以來學習下，希望你能有所收獲。

【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制“1”，表示點陣的文字。用二進制的“0”，表示非文字的空白塊。以Asc5x8的“！”為例進行講解：

0x20,0x20,0x20,0x20,0x20,0x00,0x20,0x00, // -!-

對應的點陣為：

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，所以用一個字節表示就可以了。如果寬度超過一個字節，那么如何計算需要多少個字節才能表示寬度呢？原則是，寬度的表示必須為字節的倍數。如寬度為9，那么超過一個字節，所以用2個字節表示。

總結寬度所需字節計算公式如下：

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數，由于寬度為24，故需要3個字節表示。j記錄縱向（高度）位置。代碼的處理，就是通過一個畫線函數進行的。每次以字節為單位(變量k處理)，對“1”進行檢測，檢測到1后，記錄k的位置。

【調用方法】

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(在構造函數中)

cf = new CustomFont();

(3) 調用方法(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。

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