AlertDialog源代码有以下方法:
static int resolveDialogTheme(Context context, int resid) {
if (resid == THEME_TRADITIONAL) {
return com.android.internal.R.style.Theme_Dialog_Alert;
} else if (resid == THEME_HOLO_DARK) {
return com.android.internal.R.style.Theme_Holo_Dialog_Alert;
} else if (resid == THEME_HOLO_LIGHT) {
return com.android.internal.R.style.Theme_Holo_Light_Dialog_Alert;
} else if (resid == THEME_DEVICE_DEFAULT_DARK) {
return com.android.internal.R.style.Theme_DeviceDefault_Dialog_Alert;
} else if (resid == THEME_DEVICE_DEFAULT_LIGHT) {
return com.android.internal.R.style.Theme_DeviceDefault_Light_Dialog_Alert;
} else if (resid >= 0x01000000) { // start of real resource IDs.
return resid;
} else {
TypedValue outValue = new TypedValue();
context.getTheme().resolveAttribute(com.android.internal.R.attr.alertDialogTheme,
outValue, true);
return outValue.resourceId;
}
}
0x01000000(我明白它是2 ^ 24)是什么意思?什么表达式resid> = 0x0100000检查?为什么渣油应该大于0x01000000到“实际资源ID的开始”?
答案 0 :(得分:5)
Android资源ID的第24-31位是包ID。
包ID从1开始,0表示这不是基础包。
所以0x01000000是实际资源ID的开始"。
见上面的评论" uint32_t id;" " struct ResTable_package"在android frameworks source file。
" struct ResTable_package"定义如下。
/**
* A collection of resource data types within a package. Followed by
* one or more ResTable_type and ResTable_typeSpec structures containing the
* entry values for each resource type.
*/
struct ResTable_package
{
struct ResChunk_header header;
// If this is a base package, its ID. Package IDs start
// at 1 (corresponding to the value of the package bits in a
// resource identifier). 0 means this is not a base package.
uint32_t id;
// Actual name of this package, \0-terminated.
char16_t name[128];
// Offset to a ResStringPool_header defining the resource
// type symbol table. If zero, this package is inheriting from
// another base package (overriding specific values in it).
uint32_t typeStrings;
// Last index into typeStrings that is for public use by others.
uint32_t lastPublicType;
// Offset to a ResStringPool_header defining the resource
// key symbol table. If zero, this package is inheriting from
// another base package (overriding specific values in it).
uint32_t keyStrings;
// Last index into keyStrings that is for public use by others.
uint32_t lastPublicKey;
};