android TP虚拟按键

在TP的driver中，报虚拟按键的方法常见的有两种：

1.直接报键值（kernel的）

2.报一个坐标，上层通过KL的解析来判定是哪个键。

下面说下第二种：

TP的kl被存放在/sys/board_properties/virtualkeys.devicename中，pull出来后可以看看内容：

0x01:139:100:900:40:60:0x01:158:400:900:40:60

可以发现就是在驱动代码中写的范围，分别是中心点X，中心点Y，宽度和高度，其实就是一个矩形区域，以X,Y为中心点，分别延伸 w/2, h/2。

4.0上对此kl的解析是在virtualkeymap.cpp中:

     do {
                String8 token = mTokenizer->nextToken(WHITESPACE_OR_FIELD_DELIMITER);
                if (token != "0x01") {
                    LOGE("%s: Unknown virtual key type, expected 0x01.",
                          mTokenizer->getLocation().string());
                    return BAD_VALUE;
                }

                VirtualKeyDefinition defn;
                bool success = parseNextIntField(&defn.scanCode)
                        && parseNextIntField(&defn.centerX)
                        && parseNextIntField(&defn.centerY)
                        && parseNextIntField(&defn.width)
                        && parseNextIntField(&defn.height);
                if (!success) {
                    LOGE("%s: Expected 5 colon-delimited integers in virtual key definition.",
                          mTokenizer->getLocation().string());
                    return BAD_VALUE;
                }

0X01是标志位，接下来的一位是scancode，再接下来就是xywh。

需要注意的是实际的范围是[x-w/2,x+w/2]  ,[y-h/2,y+h/2].

2.3.5上是在inputmanager.java中getVirtualKeyDefinitions方法中解析的：

  try {
                FileInputStream fis = new FileInputStream(
                        "/sys/board_properties/virtualkeys." + deviceName);
                InputStreamReader isr = new InputStreamReader(fis);
                BufferedReader br = new BufferedReader(isr, 2048);
                String str = br.readLine();
                if (str != null) {
                    String[] it = str.split(":");
                    if (DEBUG_VIRTUAL_KEYS) Slog.v(TAG, "***** VIRTUAL KEYS: " + it);
                    final int N = it.length-6;
                    for (int i=0; i<=N; i+=6) {
                        if (!"0x01".equals(it[i])) {
                            Slog.w(TAG, "Unknown virtual key type at elem #"      + i + ": " + it[i] + " for device " + deviceName);
                            continue;
                        }
                        try {
                            VirtualKeyDefinition key = new VirtualKeyDefinition();
                            key.scanCode = Integer.parseInt(it[i+1]);
                            key.centerX = Integer.parseInt(it[i+2]);
                            key.centerY = Integer.parseInt(it[i+3]);
                            key.width = Integer.parseInt(it[i+4]);
                            key.height = Integer.parseInt(it[i+5]);
                            if (DEBUG_VIRTUAL_KEYS) Slog.v(TAG, "Virtual key "
                                    + key.scanCode + ": center=" + key.centerX + ","  + key.centerY + " size=" + key.width + "x"
                                    + key.height);
                            keys.add(key);
                        } catch (NumberFormatException e) {
                            Slog.w(TAG, "Bad number in virtual key definition at region "
                                    + i + " in: " + str + " for device " + deviceName, e);
                        }
                    }
                }
                br.close();   } catch (FileNotFoundException e) {
                Slog.i(TAG, "No virtual keys found for device " + deviceName + ".");
            } catch (IOException e) {
                Slog.w(TAG, "Error reading virtual keys for device " + deviceName + ".", e);
            }
            
            return keys.toArray(new VirtualKeyDefinition[keys.size()]);
        }

实际是在inputread中使用：

 TouchInputMapper::configureVirtualKeysLocked()方法中会计算出每个虚拟按键对应的矩形范围，并将scancode转换成keycode。