RasmView - an Android drawing view; it provides a view that allows users to draw on top of a bitmap.

Raed Mughaus

Last update: Dec 23, 2022

Overview

RasmView

RasmView is an Android drawing library; it provides a view that allows users to draw on top of a bitmap.

Demo

https://www.youtube.com/watch?v=8qYhwjleT_8

Features

8 already defined brushes, and you can define your own.
Drawing on top of images.
Undo/redo operations.
Zooming in/out, rotation & translation.
Custom background color.

Download

Gradle:

dependencies {
  implementation 'com.raedapps:rasmview:1.2.0'
}

Maven:

<dependency>
  <groupId>com.raedappsgroupId>
  <artifactId>rasmviewartifactId>
  <version>1.2.0version>
dependency>

Usage Guide

Add the following to your layout file:

RasmContext

RasmContext allows you to control the brush configuration, undo/redo, reset transformation, and more. RasmContext can be accessed from RasmView:

val rasmView = findViewById<RasmView>(R.id.rasmView)
val rasmContext = rasmView.rasmContext

Changing the brush

You can use the BrushesRepository to get an already defined brush.

val brushesRepository = BrushesRepository(resources)
rasmContext.brushConfig = brushesRepository.get(Brush.Marker)

The following brushes are already defined:

enum class Brush {
    Pencil,
    Pen,
    Calligraphy,
    AirBrush,
    Marker,
    HardEraser,
    SoftEraser,
}

Brush color

Here is how to change the brush color:

rasmContext.brushColor = Color.RED
rasmContext.brushColor = 0xff2187bb.toInt() //ARGB

The alpha channel value is ignored, you can control alpha by setting brushConfig.flow.

Brush size and other configurations

val brushConfig = rasmContext.brushConfig
brushConfig.size = 0.5f
brushConfig.flow = 0.25f
brushConfig.isEraser = true

Custom brushes

val myStampBitmap = ...
val customBrushConfig = BrushConfig()
customBrushConfig.stamp = BrushStamp.BitmapStamp(myStampBitmap)
customBrushConfig.size = 0.25f
customBrushConfig.spacing = 0.1f
rasmContext.brushConfig = customBrushConfig

Drawing on a bitmap (your own image).

val imageBitmap = ... //load your bitmap whether from a URI or resources
rasmContext.setRasm(imageBitmap)
rasmView.resetTransformation()

Getting the drawing

val drawingBitmap = rasmContext.exportRasm()

Background color

rasmContext.setBackgroundColor(Color.BLACK)

Undo/redo

val rasmState = rasmContext.state
rasmState.undo()
rasmState.redo()

But you do not want to keep your buttons enabled when an undo/redo is not possible, you can listen to state updates:

undoButton.setOnClickListener {
    rasmState.undo()
}
redoButton.setOnClickListener {
    rasmState.redo()
}
rasmState.addOnStateChangedListener {
    undoButton.isEnabled = rasmState.canCallUndo()
    redoButton.isEnabled = rasmState.canCallRedo()
}
undoButton.isEnabled = rasmState.canCallUndo()
redoButton.isEnabled = rasmState.canCallRedo()

Clearing the drawing

rasmContext.clear()

Enabling rotation

rasmContext.rotationEnabled = true

Resetting the transformation

rasmView.resetTransformation()

If you found a bug, please open an issue.

License

Copyright 2022 Raed Mughaus

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

   http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.

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