Pan shift

app/src/main/res/layout/activity_main.xml

@@ -15,6 +15,9 @@
         app:hasClickableChildren="true"
         app:horizontalPanEnabled="true"
         app:verticalPanEnabled="true"
+        app:panVerticalPadding="200"
+        app:panHorizontalPadding="100"
+        app:overpanFactor=".3"
         app:zoomEnabled="true">
 
         <com.otaliastudios.zoom.demo.ColorGridView

library/src/main/java/com/otaliastudios/zoom/ZoomApi.kt

@@ -411,6 +411,12 @@ interface ZoomApi {
      */
     fun cancelAnimations(): Boolean
 
+    fun setPanVerticalPadding(padding: Int)
+
+    fun setPanHorizontalPadding(padding: Int)
+
+    fun setOverpanFactor(factor: Float)
+
     companion object {
 
         /**
@@ -489,5 +495,8 @@ interface ZoomApi {
          * The default value for [setAlignment].
          */
         const val ALIGNMENT_DEFAULT = com.otaliastudios.zoom.Alignment.CENTER
+
+        const val PAN_VERTICAL_PADDING_DEFAULT = 0
+        const val PAN_HORIZONTAL_PADDING_DEFAULT = 0
     }
 }

library/src/main/java/com/otaliastudios/zoom/ZoomEngine.kt

@@ -4,13 +4,16 @@ import android.annotation.SuppressLint
 import android.content.Context
 import android.graphics.Matrix
 import android.graphics.RectF
-import android.view.*
+import android.view.Gravity
+import android.view.MotionEvent
+import android.view.View
+import android.view.ViewTreeObserver
 import com.otaliastudios.zoom.ZoomApi.*
-import com.otaliastudios.zoom.internal.UpdatesDispatcher
-import com.otaliastudios.zoom.internal.matrix.MatrixController
 import com.otaliastudios.zoom.internal.StateController
+import com.otaliastudios.zoom.internal.UpdatesDispatcher
 import com.otaliastudios.zoom.internal.gestures.PinchDetector
 import com.otaliastudios.zoom.internal.gestures.ScrollFlingDetector
+import com.otaliastudios.zoom.internal.matrix.MatrixController
 import com.otaliastudios.zoom.internal.matrix.MatrixUpdate
 import com.otaliastudios.zoom.internal.movement.PanManager
 import com.otaliastudios.zoom.internal.movement.ZoomManager
@@ -568,6 +571,19 @@ internal constructor(context: Context) : ZoomApi {
         matrixController.setContainerSize(width, height, applyTransformation)
     }
 
+
+    override fun setPanVerticalPadding(padding: Int) {
+        panManager.panVerticalPadding = padding
+    }
+
+    override fun setPanHorizontalPadding(padding: Int) {
+        panManager.panHorizontalPadding = padding
+    }
+
+    override fun setOverpanFactor(factor: Float) {
+        panManager.overpanFactor = factor
+    }
+
     /**
      * Clears the current state, and stops dispatching matrix events
      * until the view is laid out again and [ZoomEngine.setContentSize]

library/src/main/java/com/otaliastudios/zoom/ZoomImageView.kt

@@ -10,6 +10,7 @@ import android.view.MotionEvent
 import android.widget.ImageView
 import androidx.annotation.AttrRes
 import com.otaliastudios.zoom.ZoomApi.ZoomType
+import com.otaliastudios.zoom.internal.movement.PanManager
 
 
 /**
@@ -55,6 +56,9 @@ open class ZoomImageView private constructor(
         val transformationGravity = a.getInt(R.styleable.ZoomEngine_transformationGravity, ZoomApi.TRANSFORMATION_GRAVITY_AUTO)
         val alignment = a.getInt(R.styleable.ZoomEngine_alignment, ZoomApi.ALIGNMENT_DEFAULT)
         val animationDuration = a.getInt(R.styleable.ZoomEngine_animationDuration, ZoomEngine.DEFAULT_ANIMATION_DURATION.toInt()).toLong()
+        val horizontalPadding = a.getInt(R.styleable.ZoomEngine_panHorizontalPadding, ZoomApi.PAN_HORIZONTAL_PADDING_DEFAULT)
+        val verticalPadding = a.getInt(R.styleable.ZoomEngine_panVerticalPadding, ZoomApi.PAN_VERTICAL_PADDING_DEFAULT)
+        val overpanFactor = a.getFloat(R.styleable.ZoomEngine_overpanFactor, PanManager.DEFAULT_OVERPAN_FACTOR)
         a.recycle()
 
         engine.setContainer(this)
@@ -84,6 +88,9 @@ open class ZoomImageView private constructor(
         setAnimationDuration(animationDuration)
         setMinZoom(minZoom, minZoomMode)
         setMaxZoom(maxZoom, maxZoomMode)
+        setPanHorizontalPadding(horizontalPadding)
+        setPanVerticalPadding(verticalPadding)
+        setOverpanFactor(overpanFactor)
 
         imageMatrix = mMatrix
         scaleType = ScaleType.MATRIX

library/src/main/java/com/otaliastudios/zoom/ZoomLayout.kt

@@ -5,10 +5,14 @@ import android.content.Context
 import android.graphics.Canvas
 import android.graphics.Matrix
 import android.util.AttributeSet
-import android.view.*
+import android.view.MotionEvent
+import android.view.View
+import android.view.ViewGroup
+import android.view.ViewTreeObserver
 import android.widget.FrameLayout
 import androidx.annotation.AttrRes
 import com.otaliastudios.zoom.ZoomApi.ZoomType
+import com.otaliastudios.zoom.internal.movement.PanManager
 
 
 /**
@@ -63,6 +67,9 @@ open class ZoomLayout private constructor(
         val transformationGravity = a.getInt(R.styleable.ZoomEngine_transformationGravity, ZoomApi.TRANSFORMATION_GRAVITY_AUTO)
         val alignment = a.getInt(R.styleable.ZoomEngine_alignment, ZoomApi.ALIGNMENT_DEFAULT)
         val animationDuration = a.getInt(R.styleable.ZoomEngine_animationDuration, ZoomEngine.DEFAULT_ANIMATION_DURATION.toInt()).toLong()
+        val horizontalPadding = a.getInt(R.styleable.ZoomEngine_panHorizontalPadding, ZoomApi.PAN_HORIZONTAL_PADDING_DEFAULT)
+        val verticalPadding = a.getInt(R.styleable.ZoomEngine_panVerticalPadding, ZoomApi.PAN_VERTICAL_PADDING_DEFAULT)
+        val overpanFactor = a.getFloat(R.styleable.ZoomEngine_overpanFactor, PanManager.DEFAULT_OVERPAN_FACTOR)
         a.recycle()
 
         engine.setContainer(this)
@@ -88,6 +95,9 @@ open class ZoomLayout private constructor(
         setMinZoom(minZoom, minZoomMode)
         setMaxZoom(maxZoom, maxZoomMode)
         setHasClickableChildren(hasChildren)
+        setPanHorizontalPadding(horizontalPadding)
+        setPanVerticalPadding(verticalPadding)
+        setOverpanFactor(overpanFactor)
 
         setWillNotDraw(false)
     }

library/src/main/java/com/otaliastudios/zoom/ZoomSurfaceView.kt

@@ -2,15 +2,18 @@ package com.otaliastudios.zoom
 
 import android.annotation.SuppressLint
 import android.content.Context
-import android.graphics.*
+import android.graphics.Color
+import android.graphics.Matrix
+import android.graphics.RectF
+import android.graphics.SurfaceTexture
 import android.opengl.GLSurfaceView
 import android.os.Build
 import android.util.AttributeSet
-import android.view.*
+import android.view.MotionEvent
+import android.view.Surface
 import androidx.annotation.RequiresApi
 import androidx.annotation.UiThread
 import androidx.annotation.WorkerThread
-import com.otaliastudios.zoom.ZoomApi.ZoomType
 import com.otaliastudios.opengl.core.EglConfigChooser
 import com.otaliastudios.opengl.core.EglContextFactory
 import com.otaliastudios.opengl.draw.GlRect
@@ -19,6 +22,8 @@ import com.otaliastudios.opengl.extensions.scale
 import com.otaliastudios.opengl.extensions.translate
 import com.otaliastudios.opengl.program.GlFlatProgram
 import com.otaliastudios.opengl.program.GlTextureProgram
+import com.otaliastudios.zoom.ZoomApi.ZoomType
+import com.otaliastudios.zoom.internal.movement.PanManager
 import javax.microedition.khronos.egl.EGLConfig
 import javax.microedition.khronos.opengles.GL10
 
@@ -175,6 +180,9 @@ open class ZoomSurfaceView private constructor(
         val transformationGravity = a.getInt(R.styleable.ZoomEngine_transformationGravity, ZoomApi.TRANSFORMATION_GRAVITY_AUTO)
         val alignment = a.getInt(R.styleable.ZoomEngine_alignment, ZoomApi.ALIGNMENT_DEFAULT)
         val animationDuration = a.getInt(R.styleable.ZoomEngine_animationDuration, ZoomEngine.DEFAULT_ANIMATION_DURATION.toInt()).toLong()
+        val horizontalPadding = a.getInt(R.styleable.ZoomEngine_panHorizontalPadding, ZoomApi.PAN_HORIZONTAL_PADDING_DEFAULT)
+        val verticalPadding = a.getInt(R.styleable.ZoomEngine_panVerticalPadding, ZoomApi.PAN_VERTICAL_PADDING_DEFAULT)
+        val overpanFactor = a.getFloat(R.styleable.ZoomEngine_overpanFactor, PanManager.DEFAULT_OVERPAN_FACTOR)
         a.recycle()
 
         engine.setContainer(this)
@@ -202,6 +210,9 @@ open class ZoomSurfaceView private constructor(
         setAnimationDuration(animationDuration)
         setMinZoom(minZoom, minZoomMode)
         setMaxZoom(maxZoom, maxZoomMode)
+        setPanHorizontalPadding(horizontalPadding)
+        setPanVerticalPadding(verticalPadding)
+        setOverpanFactor(overpanFactor)
 
         setEGLContextFactory(EglContextFactory.GLES2)
         setEGLConfigChooser(EglConfigChooser.GLES2)

library/src/main/java/com/otaliastudios/zoom/internal/movement/PanManager.kt

@@ -2,7 +2,9 @@ package com.otaliastudios.zoom.internal.movement
 
 import android.annotation.SuppressLint
 import android.view.Gravity
-import com.otaliastudios.zoom.*
+import com.otaliastudios.zoom.Alignment
+import com.otaliastudios.zoom.ScaledPoint
+import com.otaliastudios.zoom.ZoomApi
 import com.otaliastudios.zoom.internal.matrix.MatrixController
 import kotlin.math.min
 
@@ -23,6 +25,9 @@ internal class PanManager(provider: () -> MatrixController) : MovementManager(pr
     internal var horizontalPanEnabled = true
     internal var verticalPanEnabled = true
     internal var alignment = ZoomApi.ALIGNMENT_DEFAULT
+    internal var panVerticalPadding = 0
+    internal var panHorizontalPadding = 0
+    internal var overpanFactor = DEFAULT_OVERPAN_FACTOR
 
     /** whether overpan is enabled, horizontally or vertically */
     override val isOverEnabled get() = horizontalOverPanEnabled || verticalOverPanEnabled
@@ -58,7 +63,9 @@ internal class PanManager(provider: () -> MatrixController) : MovementManager(pr
         val fix = checkBounds(horizontal, false).toInt()
         val alignment = if (horizontal) Alignment.getHorizontal(alignment) else Alignment.getVertical(alignment)
         @Suppress("CascadeIf")
-        if (contentDim > containerDim) {
+        if (contentDim > containerDim &&
+                panHorizontalPadding == ZoomApi.PAN_HORIZONTAL_PADDING_DEFAULT &&
+                panVerticalPadding == ZoomApi.PAN_VERTICAL_PADDING_DEFAULT) {
             // Content is bigger. We can move between 0 and extraSpace, but since our pans
             // are negative, we must invert the sign.
             val extraSpace = contentDim - containerDim
@@ -139,7 +146,8 @@ internal class PanManager(provider: () -> MatrixController) : MovementManager(pr
         }
         min -= overScroll
         max += overScroll
-        val desired = value.coerceIn(min, max)
+        val padding = if (horizontal) panHorizontalPadding else panVerticalPadding
+        val desired = value.coerceIn(min - padding, max + padding)
         return desired - value
     }
 
@@ -150,8 +158,8 @@ internal class PanManager(provider: () -> MatrixController) : MovementManager(pr
     @ZoomApi.ScaledPan
     internal val maxOverPan: Float
         get() {
-            val overX = controller.containerWidth * DEFAULT_OVERPAN_FACTOR
-            val overY = controller.containerHeight * DEFAULT_OVERPAN_FACTOR
+            val overX = controller.containerWidth * overpanFactor
+            val overY = controller.containerHeight * overpanFactor
             return min(overX, overY)
         }
 
@@ -184,6 +192,6 @@ internal class PanManager(provider: () -> MatrixController) : MovementManager(pr
         /**
          * The default overscrolling factor
          */
-        private const val DEFAULT_OVERPAN_FACTOR = 0.10f
+        internal const val DEFAULT_OVERPAN_FACTOR = 0.10f
     }
 }

library/src/main/res/values/attrs.xml

@@ -54,6 +54,9 @@
             <flag name="none" value="0x44" />
         </attr>
         <attr name="animationDuration" format="integer" />
+        <attr name="panVerticalPadding" format="integer" />
+        <attr name="panHorizontalPadding" format="integer" />
+        <attr name="overpanFactor" format="float"/>
     </declare-styleable>
 
 </resources>