feat: 优化代码

app/src/main/java/io/legado/app/ui/book/read/ReadBookActivity.kt

@@ -344,13 +344,13 @@ class ReadBookActivity : VMBaseActivity<ReadBookViewModel>(R.layout.activity_boo
     override fun upSelectedStart(x: Float, y: Float) {
         cursor_left.x = x - cursor_left.width
         cursor_left.y = y
-        cursor_left.visible()
+        cursor_left.visible(true)
     }
 
     override fun upSelectedEnd(x: Float, y: Float) {
         cursor_right.x = x
         cursor_right.y = y
-        cursor_right.visible()
+        cursor_right.visible(true)
     }
 
     override fun onCancelSelect() {

app/src/main/java/io/legado/app/utils/ViewExtensions.kt

@@ -50,10 +50,10 @@ fun View.visible() {
 }
 
 fun View.visible(visible: Boolean) {
-    visibility = if (visible) {
-        VISIBLE
-    } else {
-        INVISIBLE
+    if (visible && visibility != VISIBLE) {
+        visibility = VISIBLE
+    } else if (!visible && visibility == VISIBLE) {
+        visibility = INVISIBLE
     }
 }