[Slider] Add new tick visibility modes

Author: pubiqq

catalog/java/io/material/catalog/slider/res/layout/cat_slider_demo_discrete.xml

@@ -163,7 +163,7 @@
         android:valueFrom="0"
         android:valueTo="10"
         android:stepSize="1"
-        app:tickVisible="false"/>
+        app:tickVisibilityMode="hidden" />
     </LinearLayout>
 
     <com.google.android.material.materialswitch.MaterialSwitch

docs/components/Slider.md

@@ -333,17 +333,20 @@ Element       | Attribute           | Related method(s)
 
 #### Tick mark attributes
 
-Element                             | Attribute               | Related method(s)                                       | Default value
------------------------------------ | ----------------------- | ------------------------------------------------------- | -------------
-**Color**                           | `app:tickColor`         | `setTickTintList`<br/>`getTickTintList`                 | `null`
-**Color for track's active part**   | `app:tickColorActive`   | `setTickActiveTintList`<br/>`getTickActiveTintList`     | `?attr/colorSurfaceVariant`
-**Color for track's inactive part** | `app:tickColorInactive` | `setTickInactiveTintList`<br/>`getTickInactiveTintList` | `?attr/colorPrimary`
-**Tick visible**                    | `app:tickVisible`       | `setTickVisible`<br/>`isTickVisible()`                  | `true`
+Element                             | Attribute                | Related method(s)                                       | Default value
+----------------------------------- | ------------------------ | ------------------------------------------------------- | -------------
+**Color**                           | `app:tickColor`          | `setTickTintList`<br/>`getTickTintList`                 | `null`
+**Color for track's active part**   | `app:tickColorActive`    | `setTickActiveTintList`<br/>`getTickActiveTintList`     | `?attr/colorSurfaceVariant`
+**Color for track's inactive part** | `app:tickColorInactive`  | `setTickInactiveTintList`<br/>`getTickInactiveTintList` | `?attr/colorPrimary`
+**Tick visible** (deprecated)       | `app:tickVisible`        | `setTickVisible`<br/>`isTickVisible()`                  | `true`
+**Tick visibility mode**            | `app:tickVisibilityMode` | `setTickVisibilityMode`<br/>`getTickVisibilityMode()`   | `autoLimit`
 
 **Note:** `app:tickColor` takes precedence over `app:tickColorActive` and
-`app:tickColorInative`. It's a shorthand for setting both values to the same
+`app:tickColorInactive`. It's a shorthand for setting both values to the same
 thing.
 
+**Note:** `app:tickVisible` is deprecated in favor of `app:tickVisibilityMode`.
+
 #### Styles
 
 Element           | Style

lib/java/com/google/android/material/slider/BaseSlider.java

@@ -24,6 +24,10 @@
 import static com.google.android.material.slider.LabelFormatter.LABEL_GONE;
 import static com.google.android.material.slider.LabelFormatter.LABEL_VISIBLE;
 import static com.google.android.material.slider.LabelFormatter.LABEL_WITHIN_BOUNDS;
+import static com.google.android.material.slider.TickVisibilityMode.TICK_VISIBILITY_AUTO_HIDE;
+import static com.google.android.material.slider.TickVisibilityMode.TICK_VISIBILITY_AUTO_LIMIT;
+import static com.google.android.material.slider.TickVisibilityMode.TICK_VISIBILITY_HIDDEN;
+import static com.google.android.material.slider.TickVisibilityMode.TICK_VISIBILITY_VISIBLE_ALL;
 import static com.google.android.material.theme.overlay.MaterialThemeOverlay.wrap;
 import static java.lang.Float.compare;
 import static java.lang.Math.abs;
@@ -301,7 +305,7 @@ private interface TooltipDrawableFactory {
   private int focusedThumbIdx = -1;
   private float stepSize = 0.0f;
   private float[] ticksCoordinates;
-  private boolean tickVisible = true;
+  private int tickVisibilityMode;
   private int trackWidth;
   private boolean forceDrawCompatHalo;
   private boolean isLongPress = false;
@@ -481,7 +485,10 @@ private void processAttributes(Context context, AttributeSet attrs, int defStyle
             ? haloColor
             : AppCompatResources.getColorStateList(context, R.color.material_slider_halo_color));
 
-    tickVisible = a.getBoolean(R.styleable.Slider_tickVisible, true);
+    tickVisibilityMode = a.hasValue(R.styleable.Slider_tickVisibilityMode)
+        ? a.getInt(R.styleable.Slider_tickVisibilityMode, -1)
+        : convertToTickVisibilityMode(a.getBoolean(R.styleable.Slider_tickVisible, true));
+
     boolean hasTickColor = a.hasValue(R.styleable.Slider_tickColor);
     int tickColorInactiveRes =
         hasTickColor ? R.styleable.Slider_tickColor : R.styleable.Slider_tickColorInactive;
@@ -1485,22 +1492,61 @@ public void setTickInactiveTintList(@NonNull ColorStateList tickColor) {
   /**
    * Returns whether the tick marks are visible. Only used when the slider is in discrete mode.
    *
-   * @see #setTickVisible(boolean)
    * @attr ref com.google.android.material.R.styleable#Slider_tickVisible
    */
   public boolean isTickVisible() {
-    return tickVisible;
+    switch (tickVisibilityMode) {
+      case TICK_VISIBILITY_VISIBLE_ALL:
+      case TICK_VISIBILITY_AUTO_LIMIT:
+        return true;
+      case TICK_VISIBILITY_AUTO_HIDE:
+        return getDesiredTickCount() <= getMaxTickCount();
+      case TICK_VISIBILITY_HIDDEN:
+        return false;
+      default:
+        throw new RuntimeException("isTickVisible() is not implemented for tickVisibilityMode=" + tickVisibilityMode);
+    }
   }
 
   /**
    * Sets whether the tick marks are visible. Only used when the slider is in discrete mode.
    *
    * @param tickVisible The visibility of tick marks.
    * @attr ref com.google.android.material.R.styleable#Slider_tickVisible
+   * @deprecated Use {@link #setTickVisibilityMode(int)} instead.
    */
+  @Deprecated
   public void setTickVisible(boolean tickVisible) {
-    if (this.tickVisible != tickVisible) {
-      this.tickVisible = tickVisible;
+    setTickVisibilityMode(convertToTickVisibilityMode(tickVisible));
+  }
+
+  @TickVisibilityMode
+  private int convertToTickVisibilityMode(boolean tickVisible) {
+    return tickVisible
+        ? TICK_VISIBILITY_AUTO_LIMIT
+        : TICK_VISIBILITY_HIDDEN;
+  }
+
+  /**
+   * Returns the current tick visibility mode.
+   *
+   * @see #setTickVisibilityMode(int)
+   * @attr ref com.google.android.material.R.styleable#Slider_tickVisibilityMode
+   */
+  @TickVisibilityMode
+  public int getTickVisibilityMode() {
+    return tickVisibilityMode;
+  }
+
+  /**
+   * Sets the tick visibility mode. Only used when the slider is in discrete mode.
+   *
+   * @see #getTickVisibilityMode()
+   * @attr ref com.google.android.material.R.styleable#Slider_tickVisibilityMode
+   */
+  public void setTickVisibilityMode(@TickVisibilityMode int tickVisibilityMode) {
+    if (this.tickVisibilityMode != tickVisibilityMode) {
+      this.tickVisibilityMode = tickVisibilityMode;
       postInvalidate();
     }
   }
@@ -1675,24 +1721,58 @@ protected void onSizeChanged(int w, int h, int oldw, int oldh) {
     updateHaloHotspot();
   }
 
-  private void maybeCalculateTicksCoordinates() {
+  private void updateTicksCoordinates() {
     if (stepSize <= 0.0f) {
+      updateTicksCoordinates(/* tickCount= */ 0);
       return;
     }
 
-    validateConfigurationIfDirty();
+    final int tickCount;
+    switch (tickVisibilityMode) {
+      case TICK_VISIBILITY_VISIBLE_ALL:
+        tickCount = getDesiredTickCount();
+        break;
+      case TICK_VISIBILITY_AUTO_LIMIT:
+        tickCount = min(getDesiredTickCount(), getMaxTickCount());
+        break;
+      case TICK_VISIBILITY_AUTO_HIDE:
+        int desiredTickCount = getDesiredTickCount();
+        tickCount = desiredTickCount <= getMaxTickCount() ? desiredTickCount : 0;
+        break;
+      case TICK_VISIBILITY_HIDDEN:
+        tickCount = 0;
+        break;
+      default:
+        throw new RuntimeException("Calculation of tick coordinates is not implemented for tickVisibilityMode=" + tickVisibilityMode);
+    }
+
+    updateTicksCoordinates(tickCount);
+  }
+
+  private int getDesiredTickCount() {
+    return (int) ((valueTo - valueFrom) / stepSize + 1);
+  }
+
+  private int getMaxTickCount() {
+    return trackWidth / (trackHeight * 2) + 1;
+  }
+
+  private void updateTicksCoordinates(int tickCount) {
+    if (tickCount == 0) {
+      ticksCoordinates = null;
+      return;
+    }
 
-    int tickCount = (int) ((valueTo - valueFrom) / stepSize + 1);
-    // Limit the tickCount if they will be too dense.
-    tickCount = min(tickCount, trackWidth / (trackHeight * 2) + 1);
     if (ticksCoordinates == null || ticksCoordinates.length != tickCount * 2) {
       ticksCoordinates = new float[tickCount * 2];
     }
 
     float interval = trackWidth / (float) (tickCount - 1);
+    float trackCenterY = calculateTrackCenter();
+
     for (int i = 0; i < tickCount * 2; i += 2) {
       ticksCoordinates[i] = trackSidePadding + i / 2 * interval;
-      ticksCoordinates[i + 1] = calculateTrackCenter();
+      ticksCoordinates[i + 1] = trackCenterY;
     }
   }
 
@@ -1701,7 +1781,7 @@ private void updateTrackWidth(int width) {
     trackWidth = max(width - trackSidePadding * 2, 0);
 
     // Update the visible tick coordinates.
-    maybeCalculateTicksCoordinates();
+    updateTicksCoordinates();
   }
 
   private void updateHaloHotspot() {
@@ -1730,7 +1810,7 @@ protected void onDraw(@NonNull Canvas canvas) {
       validateConfigurationIfDirty();
 
       // Update the visible tick coordinates.
-      maybeCalculateTicksCoordinates();
+      updateTicksCoordinates();
     }
 
     super.onDraw(canvas);
@@ -1807,7 +1887,7 @@ private void drawActiveTrack(@NonNull Canvas canvas, int width, int yCenter) {
   }
 
   private void maybeDrawTicks(@NonNull Canvas canvas) {
-    if (!tickVisible || stepSize <= 0.0f) {
+    if (ticksCoordinates == null || ticksCoordinates.length == 0) {
       return;
     }
 

lib/java/com/google/android/material/slider/TickVisibilityMode.java

@@ -0,0 +1,42 @@
+package com.google.android.material.slider;
+
+import androidx.annotation.IntDef;
+
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+
+/**
+ * Mode to specify the visibility of tick marks.
+ */
+@IntDef({
+    TickVisibilityMode.TICK_VISIBILITY_VISIBLE_ALL,
+    TickVisibilityMode.TICK_VISIBILITY_AUTO_LIMIT,
+    TickVisibilityMode.TICK_VISIBILITY_AUTO_HIDE,
+    TickVisibilityMode.TICK_VISIBILITY_HIDDEN
+})
+@Retention(RetentionPolicy.SOURCE)
+public @interface TickVisibilityMode {
+
+  /**
+   * All tick marks will be drawn, even if they are spaced too densely.
+   */
+  int TICK_VISIBILITY_VISIBLE_ALL = 0;
+
+  /**
+   * All tick marks will be drawn if they are not spaced too densely. Otherwise, the maximum
+   * allowed number of tick marks will be drawn.
+   * Note that in this case, the drawn ticks may not match the actual snap values.
+   */
+  int TICK_VISIBILITY_AUTO_LIMIT = 1;
+
+  /**
+   * All tick marks will be drawn if they are not spaced too densely. Otherwise, the tick marks
+   * will not be drawn.
+   */
+  int TICK_VISIBILITY_AUTO_HIDE = 2;
+
+  /**
+   * Tick marks will not be drawn.
+   */
+  int TICK_VISIBILITY_HIDDEN = 3;
+}

lib/java/com/google/android/material/slider/res/values/attrs.xml

@@ -59,8 +59,24 @@
     <!-- The color of the slider's tick marks for the inactive portion of the track. Only used when
          the slider is in discrete mode. -->
     <attr name="tickColorInactive" format="color" />
-    <!-- Whether to show the tick marks. Only used when the slider is in discrete mode. -->
+    <!-- Whether to show the tick marks. Only used when the slider is in discrete mode.
+         {@deprecated Use tickVisibilityMode instead.} -->
     <attr name="tickVisible" format="boolean" />
+    <!-- Mode to specify the visibility of tick marks. Only used when the slider is in
+         discrete mode. -->
+    <attr name="tickVisibilityMode" format="enum">
+      <!-- All tick marks will be drawn, even if they are spaced too densely. -->
+      <enum name="visibleAll" value="0" />
+      <!-- All tick marks will be drawn if they are not spaced too densely. Otherwise,
+           the maximum allowed number of tick marks will be drawn.
+           Note that in this case, the drawn ticks may not match the actual snap values. -->
+      <enum name="autoLimit" value="1" />
+      <!-- All tick marks will be drawn if they are not spaced too densely. Otherwise,
+           the tick marks will not be drawn. -->
+      <enum name="autoHide" value="2" />
+      <!-- Tick marks will not be drawn. -->
+      <enum name="hidden" value="3" />
+    </attr>
     <!-- The color of the track. -->
     <attr name="trackColor" />
     <!-- The color of active portion of the track. -->