Develop Reference

Clip by mask defined by pixel image or prevent drawing outside of that mask

I'm two days into js,html and css programming. So very newbie!
Following and building upon this TUTORIAL
Q1: How can I add this male into the background (see figuere 1.) and prohibit any strokes outside of the borders?
Adding image to background was no biggy!
function make_base()
{
base_image = new Image();
base_image.src = 'img/bmapFront.gif';
base_image.onload = function(){
context.drawImage(base_image, 0,0);
}
}
There is a context.clip function, not sure if I can use pixel form as clipping path. Making tons of "image substractions" isn't the best way.
Any suggestions
Edit:
Did the Job for me: VeryHelpful
var frontPath = new Path2D ("M 133.41,17.00 C 141.37,2.41 160.66, !VERY LONG! ")
context.clip(frontPath);
Messy strokes!
He should look like this. Then I want to save him.

Although there is such a thing as ctx.clip(), this is sometimes not what's wanted as it's impractical to use a path.
The solution that I like involves creating a virtual empty canvas onto which you draw your pixel image. Through various manipulations, like using ctx.getImageData and similar to make sure you only get one kind of color or apply other filters only once, you can obtain an image that seems to be empty (alpha of 0, mostly) in the places where you want to clip other images or paths out.
At that point, you'd use ctx.globalCompositeOperation = 'source-atop', or pick another one you might want to use from mdn's list of globalCompositeOperations.
At this point, you can just draw this virtual canvas image onto the main canvas

Mouse movement parallax on Google Map?

Is it possible to add something like this to Google Maps?
This demo has parallax with multiple layers, I would need only one
for map itself.
I don't nessessarily need the code because there are few tutorials how to achieve mouse movement parallax. Im more interested how to apply this to Google Maps.
My current ideas / questions?
Would it be somehow possible to move map tiles in the background without moving Google logo?
If not, how to make map bigger (out of browser viewport) without messing up tiles so that I could move whole map and use overflow { hidden; }?
Don't worry about hiding Google's credentials or messing up controls, I could add all the divs, controls and logo myself via JS.
I would be very grateful if you used my provided jsFiddle example to make your point.

You can do this using the panTo() function. I gave it some default numbers for the scroll effect that you can change to meet your needs.
$( "#map-cover" ).on( "mousemove", function( event ) {
var newLatlng = new google.maps.LatLng(
myLatlng.lat() + event.pageY / 1000,
myLatlng.lng() + event.pageX / 1000)
map.panTo(newLatlng);
});
Make sure to add a div above the map and disable the controls on the map
Updated JSFiddle
Upon, getting additional clarification, you can add a listener to check if the map is being dragged.
map.addListener("drag", function() {
dragging = true;
});
map.addListener("dragend", function() {
dragging = false;
});
Draggable map with mouse scroll

KineticJs - Merging an image onto another

I'd like to know if there is some way in Kinetic to have an image merged with another image on a lower layer, creating a kind of crop effect based on the shape of the "cropping" image.
The image must have a transparent background as a result, which is the main source of difficulty for me. I would otherwise just have used a mask with dragging turned off... I've made a diagram to explain what I want a bit better. Any suggestions welcome.
diagram
I've also made a quick jsfiddle, where I would like the contents of the image to be displayed inside the box. I feel like one layer is the way to go on this one.

You can use an offscreen Canvas element plus compositing to create your clipped image for use by your Kinetic.Image. Note that the offscreen canvas can be used as an image source for your Kinetic.Image.
Example code and a Demo: http://jsfiddle.net/m1erickson/ks1xxqfL/
var canvas=document.createElement('canvas');
var ctx=canvas.getContext('2d');
canvas.width=background.width;
canvas.height=background.height;
ctx.drawImage(mask,0,0,mask.width*2.25,mask.height*2.25);
ctx.globalCompositeOperation='source-in';
ctx.drawImage(background,0,0);
var support=new Kinetic.Image({
draggable:true,
image:canvas,
});
layer.add(support);
layer.draw();
Illustrations
Left: the background image,
Center: the image to be used as a clipping mask
Right: the background clipped by the mask (mask was scaled by 2.25X)

is there a way to resize marker icons depending on zoom level in leaflet?

I'm making a project for the school and I need to resize the marker icons depending on zoom level in a leaflet map, Is there an easy way to accomplish this? Any tutorial on the web? Thanks in advance for the help!!!

In order to change the size of the markers when you zoom in/out, you'll need to handle the event.
map.on('zoomend', function() { });
The zoomend event will be called whenever the map has finished zooming in or out. See the API here.
Now, inside this function, you can call your custom code in order to change the size of the markers. For example, let's say you wanted to take a simple approach and set the size of a circle marker equal to the size of the maps zoom level. See the API for a CircleMarker here
// Create some marker that will be resized on the map zooming
var myMarker = new L.CircleMarker([10,10], { /* Options */ });
map.on('zoomend', function() {
var currentZoom = map.getZoom();
myMarker.setRadius(currentZoom);
});
Now whenever the map zooms in or out, the size of the marker will change.

I'm not sure what Stophace is referring to regarding circleMarkers not changing size, but, adding to the approved answer... if you want to resize circleMakers or change any other styling options (I find it helpful to change the weight along with radius), you can use the following approach:
map.on('zoomend', function() {
var currentZoom = map.getZoom();
var myRadius = currentZoom*(1/2); //or whatever ratio you prefer
var myWeight = currentZoom*(1/5); //or whatever ratio you prefer
layername.setStyle({radius: myRadius, weight: setWeight});
});
layername will be replaced with the name of whatever layer you have which contains circleMarkers... and of course you can change the fractions to your liking to suit your needs.
I'm guessing the OP's school project is finished, but I hope this helps others who have the same question!

Click on given element in canvas

Is there any trick to determine if user clicks on given element rendered in canvas? For example I'm displaying rhombus from .png file with transparent background and i want to know if user click inside or outside that figure (like mouse-element collision).

There is no concept of individual elements in a canvas - it is simply just an area that you're drawing pixels onto. SVG on the other hand is made up of elements which you can then bind events to. However there are a few approaches you can take to add click events to canvas:
Position an html element that overlays the area on the canvas you want to be clickable. A for a rectangular area or an image map for something more irregular.
Use separate canvases for each element that you want to be clickable.
CAKE - I haven't used this myself, but it's description is "SVG sans the XML". This may cover your needs. Demos here http://glimr.rubyforge.org/cake/canvas.html#EditableCurve

One idea is to draw the image to a temporary canvas, then use getImageDate() to receive data for the pixel you are interested in, and check if its alpha value is 0 ( = transparent).
The following is a sketch of a solution. It is assumed that...
x and y are the coordinates of the mouse click event
you are looping over gameObjects, the current object being stored in the variable gameObject
the game object has been initialized with an image, x and y coordinates
The following code would then check whether the click was on a transparent area:
var tempCanvas = document.createElement('canvas');
if (tempCanvas.getContext) {
tempContext = tempCanvas.getContext('2d');
}
tempContext.drawImage(gameObject.img, 0, 0);
var imgd = tempContext.getImageData(x - gameObject.x, y - gameObject.y, 1, 1);
var pix = imgd.data;
if (pix[3] == 0) {
// user clicked on transparent part of the image!
}
Note: This is probably quite inefficient. I'm sure someone can come up with a better solution.

I have solve this problem using kintech.js, tutorials and examples can be found: http://www.html5canvastutorials.com/kineticjs/html5-canvas-drag-and-drop-tutorial/