I’d like to use a Shapefile to generate an interactive world map. I was able to import the data and use CG Paths to draw the map into one large view.
The map needs to support panning, zooming and touch interaction. For that, I've created a UIScrollView and placed the MapView (large view with all of the countries drawn) into it.
I need to improve two aspects of it:
Performance / rendering
I have drawn the map much larger than the screen size, in order to make it look reasonable when I zoom in. There are a few problems with this. First, when I'm zoomed out, I need the border stroke/line to be wider so they are visible. When I zoom in, I'd like the stroke to be a thinner. Also, when I zoom in, I can still see that the map is a blurry. I don't want to increase the view size too much.
How can I make the map look crisp when I'm zoomed in? I attempted to redraw the map on zoom in, but it takes far too long. Can I somehow only re render onscreen stuff?
Touch Interaction
I need to be able to have a touch event for every different country.
Possible approach?
I was thinking of trying to separate every country onto it’s own view. That should make touches easy to handle. Then I’m thinking I can possibly redraw the appropriate views that are on screen/zoomed to.
I've played with an app that does something similar ("World Maps"), and I can see that when you pan or zoom, the map is blurry for a second but then becomes clear. What is going on there?
use mapkit and provide custom tiles. dont reinvent the wheel and try to write yet another map framework
I think that you have to create different scaled area image from the big map image. how to say... imagine the google map, how it works... I think that provide many different zoom factor image for every area of the world... then merged display on the screen while user need show it ...
use code implemented the map effect is impossible on current iPhone device, out of the ability of the iOS device
Related
I'm currently in the process of converting a custom map from using a CATiledLayer scroll view to using custom map tiles in an MKMapView with an MKTileOverlay. Whilst the CATiledLayer-approach generally works well and looks nicer, you get a lot of things for free by using an MKMapView such as rotations which are otherwise very difficult to achieve.
So, I've redrawn my tiles for use with the recommended format of zoom level, column and row numbers, and have them displaying in the map view correctly. Note that my map tiles only cover a small region somewhere; I don't have them for the entire globe.
The first problem I noticed is that there seems to be an issue when you zoom in past the largest zoom level my tiles support. I have tiles all the way to zoom level 20 so I set my MKTileOverlay's maximumZ property to 20. If you zoom in to level 21, the map view no longer requests tiles at all. Any tiles loaded on the way to level 21 still show (albeit pixelated), but if you scroll away it won't load any more tiles, so eventually the map just becomes blank. Ideally, it would fall back to my level 20 tiles and display those instead, or prevent the user from zooming in too far. When I use the CATiledLayer, you could zoom in as much as you want and it would always show the most zoomed in tiles (even if you were zoomed in further than the tiles were 'comfortable' at). Example
I have other minor niggles too:
If you set canReplaceMapContent to true, you can zoom in a lot further (which is fine), but the camera clips the ground if you get too close and I get all sorts of rendering artefacts. Any way to prevent that from happening? Example
Sometimes there are small pixel-sized rendering artefacts between tiles which indicate the tiles aren't quite positioned or sized correctly my the MKMapView. These artefacts don't seem to affect the native maps app; any way to get rid of these? Example
As you pan around when zoomed in, there are a lot of white flashes as tiles are loaded and it's quite obvious. When I used the CATiledLayer, they were loaded in quite smoothly (by animating the opacity) and the lower-zoom levels were already present in the background so it was overall difficult to tell it was even using tiles. Is there any way to load in my tiles more seamlessly? Example
I'm guessing the answer to most of these questions is that it's not possible to fix using MKMapView, which is a shame because I really want to allow the user to change the heading of the map and it seems pretty difficult to do using a standard CATiledLayer!
I need to be able to interact with a representation of a cilinder that has many different parts in it. When the users taps over on of the small rectangles, I need to display a popover related to the specific piece (form).
The next image demonstrates a realistic 3d approach. But, I repeat, I need to solve the problem, the 3d is NOT required (would be really cool though). A representation that complies the functional needs will suffice.
The info about the parts to make the drawing comes from an API (size, position, etc)
I dont need it to be realistic really. The simplest aproximation would be to show a cilinder in a 2d representation, like a rectangle made out of interactable small rectangles.
So, as I mentioned, I think there are (as I see it) two opposite approaches: Realistic or Simplified
Is there a way to achieve a nice solution in the middle? What libraries, components, frameworks that I should look into?
My research has led me to SceneKit, but I still dont know if I will be able to interact with it. Interaction is a very important part as I need to display a popover when the user taps on any small rectangle over the cylinder.
Thanks
You don't need any special frameworks to achieve an interaction like this. This effect can be achieved with standard UIKit and UIView and a little trigonometry. You can actually draw exactly your example image using 2D math and drawing. My answer is not an exact formula but involves thinking about how the shapes are defined and break the problem down into manageable steps.
A cylinder can be defined by two offset circles representing the end pieces, connected at their radii. I will use an orthographic projection meaning the cylinder doesn't appear smaller as the depth extends into the background (but you could adapt to perspective if needed). You could draw this with CoreGraphics in a UIView drawRect.
A square slice represents an angle piece of the circle, offset by an amount smaller than the length of the cylinder, but in the same direction, as in the following diagram (sorry for imprecise drawing).
This square slice you are interested in is the area outlined in solid red, outside the radius of the first circle, and inside the radius of the imaginary second circle (which is just offset from the first circle by whatever length you want the slice).
To draw this area you simply need to draw a path of the outline of each arc and connect the endpoints.
To check if a touch is inside one of these square slices:
Check if the touch point is between angle a from the origin at a.
Check if the touch point is outside the radius of the inside circle.
Check if the touch point is inside the radius of the outside circle. (Note what this means if the circles are more than a radius apart.)
To find a point to display the popover you could average the end points on the slice or find the middle angle between the two edges and offset by half the distance.
Theoretically, doing this in Scene Kit with either SpriteKit or UIKit Popovers is ideal.
However Scene Kit (and Sprite Kit) seem to be in a state of flux wherein nobody from Apple is communicating with users about the raft of issues folks are currently having with both. From relatively stable and performant Sprite Kit in iOS 8.4 to a lot of lost performance in iOS 9 seems common. Scene Kit simply doesn't seem finished, and the documentation and community are both nearly non-existent as a result.
That being said... the theory is this:
Material IDs are what's used in traditional 3D apps to define areas of an object that have different materials. Somehow these Material IDs are called "elements" in SceneKit. I haven't been able to find much more about this.
It should be possible to detect the "element" that's underneath a touch on an object, and respond accordingly. You should even be able to change the state/nature of the material on that element to indicate it's the currently selected.
When wanting a smooth, well rounded cylinder as per your example, start with a cylinder that's made of only enough segments to describe/define the material IDs you need for your "rectangular" sections to be touched.
Later you can add a smoothing operation to the cylinder to make it round, and all the extra smoothing geometry in each quadrant of unique material ID should be responsive, regardless of how you add this extra detail to smooth the presentation of the cylinder.
Idea for the "Simplified" version:
if this representation is okey, you can use a UICollectionView.
Each cell can have a defined size thanks to
collectionView:layout:sizeForItemAtIndexPath:
Then each cell of the collection could be a small rectangle representing a
touchable part of the cylinder.
and using
collectionView:(UICollectionView *)collectionView
didSelectItemAtIndexPath:(NSIndexPath *)indexPath
To get the touch.
This will help you to display the popover at the right place:
CGRect rect = [collectionView layoutAttributesForItemAtIndexPath:indexPath].frame;
Finally, you can choose the appropriate popover (if the app has to work on iPhone) here:
https://www.cocoacontrols.com/search?q=popover
Not perfect, but i think this is efficient!
Yes, SceneKit.
When user perform a touch event, that mean you knew the 2D coordinate on screen, so your only decision is to popover a view or not, even a 3D model is not exist.
First, we can logically split the requirement into two pieces, determine the touching segment, showing right "color" in each segment.
I think the use of 3D model is to determine which piece of data to show in your case if I don't get you wrong. In that case, the SCNView's hit test method will do most of work for you. What you should do is to perform a hit test, take out the hit node and the hit's local 3D coordinate of this node, you can then calculate which segment is hit by this touch and do the decision.
Now how to draw the surface of the cylinder would be the only left question, right? There are various ways to do, for example simply paint each image you need and programmatically and attach it to the cylinder's material or have your image files on disk and use as material for the cylinder ...
I think the problem would be basically solved.
I'm looking for a library/framework/toolkit that will allow me to render a 2D map from real GeoSpatial data and draw objects on the 2D map.
Requirements:
Map Tiling (when I zoom into the map, i want a more detailed image)
Pan (ability to use the mouse to move around the map)
Read various Geospatial images (satellite, street, etc)
Ability to draw objects onto the map (based on lat/longs) and have them move. For example, I want to be able to put an image of a bird on the map and have it move and rotate correctly.
Primitive shapes. It would be nice if it had built in ability to draw lines, circles, etc.
Complex drawing. For example, I want to draw a compass and have it show the heading of the current heading of the bird.
Mouse input. I want to be able to right click on the map and have a context menu appear. I want to click and hold an shape I draw on the map and drag it easily.
What I have looked at:
OpenSceneGraph with osgEarth. It's great, and fulfills my reqs, but is really slow and I had to do a lot of weird things to get things to work (especially with dragging objects on the map).
Cesium: looks promising, but somewhat slow, and I need it to work as a desktop application. I've seen online that some have managed to use Cesium inside Qt's Webkit, but I'm not sure I would want to take that risk.
EDIT:
I really want to stay away from a web-based framework if possible.
http://imgur.com/52DaJtQ
Here is a primitive picture of what I'm want to achieve. The aircraft icon should move and the degree circle along with it. I want to be able to drag the green waypoints and have the lines redraw as I move a waypoint. The red sensor footprint should adjust to what the aircraft can see.
http://imgur.com/52DaJtQ
Google Maps, Open Street Map, Bing Maps.
I use OpenSceneGraph/osgEarth extensively and am not dissatisfied with its performance.
What kind of weird things did you need to do?
If you want, you can contact me privately to troubleshoot your situation. Me website is AlphaPixel.com and there's a contact form there.
The application I am working on requires a 4px bar height with a full screen size width. I need to be able to select this 4px bar and move it around. I also can not change the size of this bar it has to be 4px in height.
This wouldn't be that big of an issue if I wasn't using OpenGL to create the object. OpenGL obviously does not have its own selection features so I am needing to program my own.
Initially after research I built a color selector to identify the object. How my color selector works is what ever x and y my finger touch returns from touchesBegan: is the pixel I grab from a screenshot of the OpenGL View. The issue with this is finger location is not precise at all. If I use the mouse it works perfect...
I decided to maybe loop through a buffer zone of the selected x and y but unfortunately a screenshot of the OpenGL view has antialiasing happens to the image when it's stored in memory and the buffer returns several shade of my objects color. I could possibly do a comparative color look up, to see if its in the range of colors but that seems overly complicated with how much I have already had to do. Plus cycling through the buffer zone isn't quick.
I also have thought maybe just remembering the location of my line on the screen and if my finger is close to that location just know that that's the one I want to select and move it around.
The future of this application can have up to 4 lines just like this so, I want something more secure then just knowing the location of where it is in memory.
What better way is there out there of handling selection of small objects?
How about maintaining an array of frames for the four objects, but expand the heights to something more manageable (8px or bigger)? Then, a touch within the larger region could be compared against the array (using CGRectContainsPoint). If you get a hit, then "snap to" the center point of the smaller (4px) rectangle before beginning the drag.
I do something like this by maintaining a list of "drop targets" for drag & drop, where it snaps to the drop target when it gets pretty close. Don't know if I'm conveying the idea very well, but it ought to work.
If the four 4px rectangles are going to be contiguous or very close together, you'll have to be able to make the selected one stand out or the user won't be able to tell which they're dragging -- but you could do that by making it bigger (maybe 6-8 px) then bringing it to the front so it overlays its adjacent neighbors.
More of an idea than an answer I guess.
John,
I would suggest a different approach. As you've discovered, touches in iOS are very imprecise. Apple usually suggests that the "hit box" for your controls be at least 40x40 points. I've gone as small as 30x30 points, but that starts to get hard.
What I would suggest you do is to factor your code so the app knows where the line is, and keeps track of it as a logical object. Then in your touch handler, interpret touches based on a large "buffer area" around the things you want the user to be able to move. If you just have a single horizontal bar, this should work great. Where you'll get into trouble is if you have multiple, thin horizontal bars that are close together. In that case you might need to rethink your app design and find another way to solve the problem.
As for the implementation details, you might add a pan gesture recognizer to your OpenGL view, and have it notify the OpenGL view of touch and drag actions. Then your OpenGL view can use knowledge of where your draggable objects are to decide how to interpret the touches.
I need to draw an interactive map for an iOs application. For example it can be the map of the US showing the states. It will need to show all the states in different colors ( I'll get this from a delegate colorForStateNo: ) It will need to allow the user to select a state by touching it, when the color will change, and a "stick out" effect should be shown, maybe even a symbol animated to appear over the selected state. Also the color of some states will need to change depending on external events. This color change will mean an animation like a circle starting in the middle of the state and progressing towards the edges changing the color from the current one to the one inside the circle.
Can this be done ,easily in core-graphics? Or is it only possible with Open GL ES? What is the easiest way to do this? I have worked with core graphics and it doesn't seem to handle animation very well, I just redraw the entire screen when something needed to move... Also how could I use an external image to draw the map? Setting up a lot of drawLineToPoint seems like , a lot of work to draw only one state let alone the whole map ...
You could create the map using vector graphics and then have that converted to OpenGL calls.
Displaying SVG in OpenGL without intermediate raster
EDIT: The link applies to C++, but you may be able to find a similar solution.