helper class to implementing a clear button for EditText views

diff --git a/app/src/main/java/net/ktnx/mobileledger/ui/TextViewClearHelper.java b/app/src/main/java/net/ktnx/mobileledger/ui/TextViewClearHelper.java
new file mode 100644 (file)
index 0000000..3060eba
--- /dev/null
+++ b/app/src/main/java/net/ktnx/mobileledger/ui/TextViewClearHelper.java
@@ -0,0 +1,135 @@
+/*
+ * Copyright © 2020 Damyan Ivanov.
+ * This file is part of MoLe.
+ * MoLe is free software: you can distribute it and/or modify it
+ * under the term of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your opinion), any later version.
+ *
+ * MoLe is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License terms for details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with MoLe. If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package net.ktnx.mobileledger.ui;
+
+import android.annotation.SuppressLint;
+import android.graphics.drawable.Drawable;
+import android.text.Editable;
+import android.text.TextWatcher;
+import android.view.MotionEvent;
+import android.view.View;
+import android.widget.EditText;
+
+import net.ktnx.mobileledger.R;
+
+public class TextViewClearHelper {
+    private boolean hadText = false;
+    private boolean hasFocus = false;
+    private EditText view;
+    private TextWatcher textWatcher;
+    private View.OnFocusChangeListener prevOnFocusChangeListener;
+    public void detachFromView() {
+        if (view == null)
+            return;
+        view.removeTextChangedListener(textWatcher);
+        prevOnFocusChangeListener = null;
+        textWatcher = null;
+        hasFocus = false;
+        hadText = false;
+        view = null;
+    }
+    @SuppressLint("ClickableViewAccessibility")
+    public void attachToTextView(EditText view) {
+        if (this.view != null)
+            detachFromView();
+        this.view = view;
+        textWatcher = new TextWatcher() {
+            @Override
+            public void beforeTextChanged(CharSequence s, int start, int count, int after) {
+
+            }
+            @Override
+            public void onTextChanged(CharSequence s, int start, int before, int count) {
+
+            }
+            @Override
+            public void afterTextChanged(Editable s) {
+                boolean hasText = s.length() > 0;
+
+                if (hasFocus) {
+                    if (hadText && !hasText)
+                        hideClearDrawable();
+                    if (!hadText && hasText)
+                        showClearDrawable();
+                }
+
+                hadText = hasText;
+
+            }
+        };
+        view.addTextChangedListener(textWatcher);
+        prevOnFocusChangeListener = view.getOnFocusChangeListener();
+        view.setOnFocusChangeListener((v, hasFocus) -> {
+            if (hasFocus) {
+                if (view.getText()
+                        .length() > 0)
+                {
+                    showClearDrawable();
+                }
+            }
+            else {
+                hideClearDrawable();
+            }
+
+            this.hasFocus = hasFocus;
+
+            if (prevOnFocusChangeListener != null)
+                prevOnFocusChangeListener.onFocusChange(v, hasFocus);
+        });
+
+        view.setOnTouchListener((v, event) -> this.onTouchEvent(view, event));
+    }
+    private void hideClearDrawable() {
+        view.setCompoundDrawablesRelative(null, null, null, null);
+    }
+    private void showClearDrawable() {
+        view.setCompoundDrawablesRelativeWithIntrinsicBounds(0, 0, R.drawable.ic_clear_black_24dp,
+                0);
+    }
+    public boolean onTouchEvent(EditText view, MotionEvent event) {
+        if ((event.getAction() == MotionEvent.ACTION_UP) && (view.getText()
+                                                                 .length() > 0))
+        {
+            boolean clearClicked = false;
+            final float x = event.getX();
+            final int vw = view.getWidth();
+            // start, top, end, bottom (end == 2)
+            Drawable dwb = view.getCompoundDrawablesRelative()[2];
+            if (dwb != null) {
+                final int dw = dwb.getBounds()
+                                  .width();
+                if (view.getLayoutDirection() == View.LAYOUT_DIRECTION_LTR) {
+                    if ((x > vw - dw))
+                        clearClicked = true;
+                }
+                else {
+                    if (x < vw - dw)
+                        clearClicked = true;
+                }
+                if (clearClicked) {
+                    view.setText("");
+                    view.requestFocus();
+                    return true;
+                }
+            }
+        }
+
+        return false;
+    }
+
+}