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J2ME 模組化 UI 框架設計（二）：Platform/Color/Style 核心常量體系

編輯：J2ME

設計理念

構建可組裝、可移植、可維護的 J2ME UI 框架，核心在於將平台差異、視覺規範、佈局參數集中定義為常量類，業務代碼零硬編碼，適配新平台只改常量類。

1. Platform 類：設備能力與鍵碼統一抽象

public class Platform extends Canvas {
    // 平台標識常量
    public static final byte PLATFORM_SUN_WTK   = 10;
    public static final byte PLATFORM_NOKIA     = 5;
    public static final byte PLATFORM_NOKIA_30  = 6; // S40 第3版
    public static final byte PLATFORM_SIEMENS   = 7;
    public static final byte PLATFORM_MOTOROLA  = 3;
    public static final byte PLATFORM_MOTOROLA_V= 4;
    public static final byte PLATFORM_SAMSUNG   = 8;
    public static final byte PLATFORM_SONYERICSSON=9;
    public static final byte PLATFORM_LG        = 2;
    public static final byte PLATFORM_BARTEO    = 1;

    // 當前目標平台 (編譯時切換/構建腳本注入)
    public static final byte PLATFORM = PLATFORM_SUN_WTK;

    // 屏幕尺寸 (運行時動態獲取)
    public static int WIDTH;
    public static int HEIGHT;

    // 雙緩衝支持
    public static final boolean DOUBLE_BUFFER = true;

    // 統一邏輯鍵碼 (映射到 Canvas 游戲動作)
    public static final int KEY_UNDEFINED   = 0;
    public static final int KEY_UP          = -1; // Canvas.UP
    public static final int KEY_DOWN        = -2; // Canvas.DOWN
    public static final int KEY_LEFT        = -3; // Canvas.LEFT
    public static final int KEY_RIGHT       = -4; // Canvas.RIGHT
    public static final int KEY_FIRE        = -5; // Canvas.FIRE
    public static final int KEY_SOFT_LEFT   = -6;
    public static final int KEY_SOFT_RIGHT  = -7;
    public static final int KEY_CLEAR       = -8;
    public static final int KEY_PHONE_ON    = -10;
    public static final int KEY_PHONE_OFF   = -11;
    public static final int KEY_ENTER       = KEY_FIRE; // 別名
    public static final int KEY_FULL_MODE   = 48;
    public static final int KEY_PAGEUP      = 42;
    public static final int KEY_PAGEDOWN    = 35;
    public static final int REFRESH         = 53;

    // 靜態初始化：啟動全屏 Canvas 獲取真實屏幕尺寸
    static {
        Canvas dummy = new Canvas() {
            protected void paint(Graphics g) {}
            protected void sizeChanged(int w, int h) {
                if (h > HEIGHT) { WIDTH = w; HEIGHT = h; }
            }
        };
        dummy.setFullScreenMode(true);
        if (dummy.getHeight() > HEIGHT) {
            WIDTH = dummy.getWidth(); HEIGHT = dummy.getHeight();
        }
        dummy = null;
    }

    // 內存工具方法
    public static long getTotalMemory() { return Runtime.getRuntime().totalMemory(); }
    public static long getFreeMemory()  { return Runtime.getRuntime().freeMemory(); }
}

2. Color 類：統一色值常量 (ARGB 格式)

public class Color {
    public static final int TRANSPARENT = 0xFFFFFFFF; // 僅 Motorola 支持
    public static final int WHITE       = 0xFEFEFE;
    public static final int DK_GRAY     = 0x555555;
    public static final int BLACK       = 0x000000;
    public static final int LT_BLUE     = 0xAACCFF; // 补充常用色
    public static final int DK_BLUE     = 0x0000AA;
    // ... 可按需擴展
}

3. Style 類：視覺風格與佈局參數總匯

public class Style {
    // 字體預定義
    public static final Font PLAIN_SMALL   = Font.getFont(Font.FACE_PROPORTIONAL, Font.STYLE_PLAIN,   Font.SIZE_SMALL);
    public static final Font PLAIN_MEDIUM  = Font.getFont(Font.FACE_PROPORTIONAL, Font.STYLE_PLAIN,   Font.SIZE_MEDIUM);
    public static final Font PLAIN_LARGE   = Font.getFont(Font.FACE_PROPORTIONAL, Font.STYLE_PLAIN,   Font.SIZE_LARGE);
    public static final Font BOLD_SMALL    = Font.getFont(Font.FACE_PROPORTIONAL, Font.STYLE_BOLD,     Font.SIZE_SMALL);
    public static final Font BOLD_MEDIUM   = Font.getFont(Font.FACE_PROPORTIONAL, Font.STYLE_BOLD,     Font.SIZE_MEDIUM);
    public static final Font BOLD_LARGE    = Font.getFont(Font.FACE_PROPORTIONAL, Font.STYLE_BOLD,     Font.SIZE_LARGE);

    // 語義化字體引用
    public static final Font TEXT_FONT        = PLAIN_SMALL;
    public static final Font HEADER_FONT      = BOLD_SMALL;
    public static final Font SOFTKEY_FONT     = BOLD_SMALL;
    public static final Font TEXT_FIELD_FONT  = TEXT_FONT;

    // 語義化色值引用
    public static final int TEXT_COLOR                   = Color.BLACK;
    public static final int BORDER_COLOR                 = Color.BLACK;
    public static final int FOCUSED_BACKGROUND_COLOR     = Color.DK_BLUE;
    public static final int FOCUSED_TEXT_COLOR           = Color.WHITE;
    public static final int CURSOR_TEXT_COLOR            = Color.BLACK;
    public static final int CURSOR_BACKGROUND_COLOR      = Color.WHITE;
    public static final int ARROW_COLOR                  = Color.BLACK;
    public static final int TITLE_BACKGROUND_COLOR       = Color.LT_BLUE;
    public static final int TITLE_TEXT_COLOR             = Color.BLACK;
    public static final int SOFTKEYBAR_BACKGROUND_COLOR  = Color.LT_BLUE;
    public static final int SOFTKEYBAR_TEXT_COLOR        = Color.BLACK;

    // 佈局間距
    public static final int V_GAP = 1;
    public static final int H_GAP = 1;
    public static final int CF_H_GAP = 1;

    // 默認背景
    public static final int BACKGROUND_COLOR = Color.TRANSPARENT;

    // 文本域滾動策略
    public static final boolean SCROLLABLE_TEXTFIELD = true;

    private Style() {} // 工具類禁止實例化
}

使用示例

// 繪製標題欄
g.setColor(Style.TITLE_BACKGROUND_COLOR);
g.fillRect(0, 0, Platform.WIDTH, Style.HEADER_FONT.getHeight() + 2*Style.V_GAP);
g.setFont(Style.HEADER_FONT);
g.setColor(Style.TITLE_TEXT_COLOR);
g.drawString(title, Platform.WIDTH/2, Style.V_GAP, Graphics.TOP | Graphics.HCENTER);

// 文本域邊框
g.setColor(Style.BORDER_COLOR);
g.drawRect(x, y, w, h);
if (focused) {
    g.setColor(Style.FOCUSED_BACKGROUND_COLOR);
    g.fillRect(x+1, y+1, w-2, h-2);
    g.setColor(Style.FOCUSED_TEXT_COLOR);
} else {
    g.setColor(Style.TEXT_COLOR);
}